In the United States, the dollar bills in general circulation come in denominations of $1, $5, $10, $20, $50, $100. These bills are all the same size, shape and texture, which makes it hard for a blind person, like Matthew, to tell the difference between the bills.
Matthew went shopping at a toy store for his nephew’s birthday. He bought a Spiderman action figure that cost $25, a LEGO City Light Repair Truck for $13, and a Despicable Me 2 DVD for $20. He went up to the counter and handed over a new crisp $100 bill to pay for these purchases. The teller handed him some number of notes in return, and Matthew knew for certain that his change was incorrect.
Which of the following is a possibility for the number of bills that the teller handed to Matthew?
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the shop keeper has to return $42 which can not be returned by 3 notes as we need atleast 4 note(20+20+1+1)
this is great
same way!!!
wow
gud one
good
exactly!
Right
is it 2 DVD or 1 DVD??
hahaha thinking of all the possibilities yet the answer was supposed to be the wrong one hahaha because the question said the change was incorrect haha
i think there's problem in understanding the question. Total cost of items bought by Matthew = $68(25$+13$+2*20$) because he bought despicable me (2) dvd )
Change that should have been given to Matthew = $22
If the change was correct, then the teller could give him 5, 4 or 3 bills.
$(20 + 1 + 1)= $22 ( 3bills)
$(10 +10 + 1 + 1) = $22 (4 bills)
$(1 + 1 +5+5+10) = $42 (5 bills)
The question says that the change given was incorrect.
Therefore, the change given to him must not be $22.
Using 2 bills we cannot total up $42.
Hence , the possibility that the number of bills that the teller handed to Matthew is 2
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And that is why you should pay attention to language. If he bought two DVDs, the word would be 'DVDs', not 'DVD'. Also the question states that 'a DVD' was bought.
The Despicable Me 2 is a movie by itself not 2 dvds
Well he bought 'Despicable Me 2 ' dvd and not 2 'Despicable Me' dvd's...
underline the word certain .....zz
The dvd is of the second part dude..but your opinion cannot be ruled out..good thinking though!! :)
Mind it Salman Buddy, they didn't say 20 dollar for each DVD. All they mentioned was 2 DVDs for 20$ !!
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no..Garima Dear..its Despicable me 2nd part dvd...(a despicable me 2 DVD for 20)...single DVD...of the 2nd part of the movie Despicable me..;)
not mentioned cost of dvd is 20 here mentioned cost of 2 dvds is 20 so u cannot sum up 2X20 so ur formation is wrong
I accidentally answered the opposite question there
you know that you are going to have two, one dollar bills no matter what.
since there is no such thing as a $40 bill then 3 bills must be the only one which is impossible. Unless he made his own $40 bill ;)
Great solution!
i think there's problem in understanding the question. Total cost of items bought by Matthew = $68(25$+13$+2*20$) because he bought despicable me (2) dvd )
Change that should have been given to Matthew = $22
If the change was correct, then the teller could give him 5, 4 or 3 bills.
$(20 + 1 + 1)= $22 ( 3bills)
$(10 +10 + 1 + 1) = $22 (4 bills)
$(1 + 1 +5+5+10) = $42 (5 bills)
The question says that the change given was incorrect.
Therefore, the change given to him must not be $22.
Using 2 bills we cannot total up $42.
Hence , the possibility that the number of bills that the teller handed to Matthew is 2
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You know, the 2 doesn't refer to the number of the DVD he bought. It's part of the movie's title.
the amount Matthew had to receive back were (40 +2)$. The 2$ can be given only in two notes of 1$. The remaining balance is 40$. Since there is no note for 40$ itself it has to be given as a combination of the available denominations. Hence the minimum number of notes given cannot be 3. hence the answer. :)
great soln
i think there's problem in understanding the question. Total cost of items bought by Matthew = $68(25$+13$+2*20$) because he bought despicable me (2) dvd )
Change that should have been given to Matthew = $22
If the change was correct, then the teller could give him 5, 4 or 3 bills.
$(20 + 1 + 1)= $22 ( 3bills)
$(10 +10 + 1 + 1) = $22 (4 bills)
$(1 + 1 +5+5+10) = $42 (5 bills)
The question says that the change given was incorrect.
Therefore, the change given to him must not be $22.
Using 2 bills we cannot total up $42.
Hence , the possibility that the number of bills that the teller handed to Matthew is 2
I got i this way.
The total shopping was of $58 and he should have gotten a change of $42.
So this means he could have received money in he following denominations $1,$5,$10 and $20.
Receiving a change of $42 is impossible if he gets only 3 notes.
Hope this helps...cheers!!!!
So the answer is 3
$25 Spiderman $13 LEGO CLRT + $20 Despicable
$58
$100-$58=$42.
The cashier owed $42 change to Matthew.
Trying the lowest of these combinations, it's obvious, that $20, $20, and $2 combination is invalid since $2 dollars are not valid. Any other bill combination will deem invalid also.
Legal bills: $1, $5, $10, $20, $50, $100. $50 is useless, $10 too low, so 2 $20's makes sense, but nothing to top off with.
Therefore, 3 is a possibility.
A change of $42 to be tendered can be done by:
6 notes ($10 x 4 notes + $1 x 2 notes)
4 notes ($20 x 2 notes + $1 x 2 notes)
5 notes ($20 x 1 note + $10 x 2 notes + $1 x 2 notes)
But no combinations, can he tender the $42 change with 3 notes.
It is very simple. The person had to return change i.e. $42. Now we look at the minimum of the option i.e. 3. The person could have returned only $41 and he would have to give one more note to make it $42.
Hence the answer is 3
This is what the blind man bought for his nephew. Spiderman action figure $25 + Truck $13 + Despicable Me 2 $20 = For a total of $58 He handed the cashier a $100 bill. This question states that in general, bills will come in $1, $5, $10, $20, $50, and $100's. Therefor, when the teller gave him the least amount of bills, he would have received two $20's and two $1 bills, which is 4 bills.
Unfortunately you did not understand the question.. Answer is 3.. :-)
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He understood it well. 4 is the minimum amount of bills Matthew would have gotten, so he could not get 3 bills.
Since that he has 100$ bill,
so the change=$10--$20-$25-$13=$42
so the probable change notes are=$1,$5,$10,$20 that is 4 of them as the change is < $50 and < $100
so by combination to fill up that $42 with bills= 4C1=4
thanks...
Since the change is $42 the cashier got to use his $1 notes twice and others me will manage. So there will be more than 2 notes for a correct cashier but since the present one is incorrect it should be three
42-cannot be formed by three notes
42-can be formed by 4 notes ($1,$1,$20,$20)
How is it that your answer is 4 ???
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U r Right. but 2 is not any option.
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The answer is 3, not 2.
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@Anish Puthuraya – The answer should be 3, and not 4
$42 can be made by 4 notes (1,1,20,20), by 5 notes(1,1,10,10,20), and by 6 notes(1,1,10,10,10,10). But not by 3 notes (1,20,20..????). So Matt knew that his change was wrong when the teller handed him 3 notes. So answer is 3.
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Exactly...I also put 3 due to the same logic and was marked incorrect....
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Hey I answered 3 and got my points....the problem has been corrected....
Me too
By the same logic I marked 3 just to see that somehow it is incorrect.. I don't understand given solution.. :(
The answer is 3. I lost my ratings too! Want it back!
Same goes for me.
By no means 4 could be the answer. I was dumb struck to see 3 incorrect.
This problem needs to be corrected, or taken down.
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I want my rating points back.. :)
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and the sum rating has gone so high because almost everyone who tried it has got it wrong.... The sum should be taken down...
me tooo!!!!
I also answered 4. But why is it 3 ?
I answered 3 :(
With 4 bills ==> 20 + 20 + 1 + 1 With 5 bills ==> 20 + 10 + 10 + 1 + 1 With 6 bills ==> 10 + 10 + 10 + 10 + 1 + 1
With 3 bills ==> No three of the bills can add up to 42. And, so the answer has to be 3.
So, has anyone posted a dispute yet?
Since the man gave the cashier a $100 bill, the amount he should get back is $100-$58=$42. 42=1+1+10+20+10 (5 notes used) 42=1+1+20+20 (4 notes used) 42=1+1+5+5+10+20 (6 notes used) Also, 42 can't be formed with 3 notes. Thus 3 is a possibility.
4C1 is the number of ways of selecting one 1 from 4 items right...there is no $ 42 bill...so if the cashier give him a single bill(any denomination)..then surely matthew can tell(and this 4C1 that is 4 (your answer is the NUMBER OF WAYS of giving matthew the wrong change by just giving him a SINGLE bill))....and similarly cashier can give him any 2 bills (that wouldn't also add up to 42 as well)...(BUT THEY ARE NOT ASKING for the possible combinations of the 2 bills AS WELL).............
(Taking one,two or three bills at a time of the given denominations will never add up to 42)
in simple words---if cashier gives Matthew a single bill or any two bills or any three bills --he can surely tell that he is being cheated...but if cashiers gives him 4,5 or 6 (or above) number of bills he cannot tell if he is being cheated...
For Example -- if cashier gives him 4 bills---- (20+20+1+1). = 42(correct change)....and also (5+5+5+5)=20(incorrect change)..or (1+1+1+1)..and so on....
so he can't tell....
but in case if is handled with one,two or three bills...then HE CAN SURELY TELL about the cheating....
so among the options 3 is correct.....because by using 4 ,5 and 6 bills at a time we can make a total of 42......
I hope u get it now....and.if not then read the question more carefully..one more time.....
The question is, how Blind person came to know that there is some mistake ?
bill was $48 so change to be returned, was 52. And 52 can't be paid in 4 notes.
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bill was 58, not 48!!!!
6 bills 10,10,10,10,1,1 or 20,10,5,5,1,1 5 bills 20,10,10,1,1 4 bills 20,20,1,1 3 bills 20,20,1 not=42 in any case
Toys has total cost of $58 so he should be changed of $42. Means, it can be $20,$20,$1 or $1 or $20,$10,$10,$1&$1 or $10,$10,$10,$10,$1,&1. Or with 4,5 or 6 number of bills.
The Teller will never return $100 or $50 bills. So we remain with $1, $5, $10, $20. Matthew gets back $(100-58)=$42. So to get wrong return he must have got * 2 $20 bills * 1 $20 bill & 2 $10 bills and so on...... but the number of bills increases a lot So the minimum no. of bills he gets back is 2 but since there is no option for 2 , I chose 3.........
Total expense = 25 + 13 + 20 = 58 Amount Mathew should receive = 100 -58 = 42 There are many ways to make up this amount But you need at least 4 bills to do it. 20+20+1+1(4 bills), 20+10+10+1+1(5 bills), 20+10+5+5+1+1(6 bills),upto (5+5+5+5)+(5+5)+(5+5)+1+1(10 bills), and then you can break up the $5 into $1 bills. This will give 5+5+5+5+5+5+5+(1+1+1+1+1)+ 1+1(14 bills) and then on you add 4 bills for every $5 you break. The sequence from 10 bills becomes 14,18, 22, 26, 30, 34, 38, and the last is 42 where everything is in $1 bills. Therefore, the wrong number is 3.
the ans is three because the minimum number of notes that the cashier can give is 4.... 2 of 20 and 2 of 2..... ;)
The total cost for the purchases are = $ ( 2 5 + 2 0 + 1 3 ) = $ 5 8
Now, since Matthew handed a $ 1 0 0 bill, so the cashier should give change = $ ( 1 0 0 − 5 8 ) = $ 4 2
Now, the cashier can give the change at the very least using 4 bills ( 2 $ 2 0 bills and 2 $ 1 bills).
But there is no way to give change using only 3 bills, so the possible number of bills that the cashier gave to Matthew = 3
The blind man's purchase add up to $58. So, the cashier must return him $42. Now, whatever be combination the cashier uses, he has to give two $1 notes to the blind man. So, there is no possibility of adding up to $42 using two $1 notes and any other denominations if only 1 more note is to be used. So, the cashier gave him 3 notes.
Matthew purchased for a sum of 58$(25+13+20) and should receive 42$ from the keeper. the minimum number of bills that make up 42$ is 4 i.e 20+20+1+1. if Matthew is sure that, what he received is wrong, then the number of bills he has is less than what he must have had. so the only possibility is that the store keeper gave him only 3 bills.
Total cost is $58, Therefore 100-58=42 Possible combination of teller returning exact bills 1) 1+1+20+20 = 4 notes ; or 2) 1+1+10+10+20 = 5 notes ; or 3) 1+1+10+10+10+10 = 6 notes since Matthew knew this change was incorrect only possibility of teller giving 3 notes remain
total amount of the purchases is 58 the remaining money is 42 so the cashier can give him [ 4 notes of 10$ and 2 notes of 1$ that makes total of 6 notes and 42$]...or....[1 note of 20$ 2 notes of 10$ and 2 notes of 1$ that makes 5 notes and 42$]...or...[2 notes of 20$ and 2 notes of 1$ that makes 4 notes and 42$] but he cannot give 3 notes
6 for $10+$10+$10+$10+$1+$1; 4 for $20+$20+$1+$1; 5 for $20+$10+$10+$1+$1; but none of the way is suitable for 3
Total cost is $58. So Matthew should get back $42.
Since U.S. dollar bills are $1, $5, $10, $20, $50, $100, two of the returned bills must be $1. To return remaining $40, the teller needs at least two bills of $20.
Therefore the minimum number of bills must be four.
So, there is a possibility that the teller handed 3 bills to Matthew.
Balance Amount Left: 42$ Minimum number of notes required = 4 i.e.(20+20+1+1) Hence 3 is the incorrect number of notes.
Total spending = 25+13+20 = 58, Amount paid = 100, balance = 100 - 58 = 42, balance is incorrect. Bills Might have given are $1, $5, $10, $20, he was not tendering exact change. it might be $1, $10, $20 or $5, $10, $20 or $1, $5, $10 or $1, $5, $20, The number of bills = 3.
minimum number of bills teller handed to the Matthew should be 4
Teller Should return = $ 42 ;
Possible combination of return amount : $1, $5, $10, $20, $50, $100
$1 + $1 + $20 + $20 = $42( possible) ; Option 4 is possible
$1 + $1 + $10 + $10 + $10 + $10 = $42 (possible) ; Option 6 is possible
but Teller cannot return $42 with sum of 3 combination. ;
teller needs to return bill 40, considering the available denominations it is not possible to return 3 bills which would amount 40 in total.
3, because it is only with 3 bills that there is no permutation of making the amount equal to the change,and since he was blind it is the only way he could have known.....
according to the currency denomination, having 3notes doesn't sumup to the left over amount of $42
Option 1 is correct: $1,$1,$10,$10,$20
Option 2 is correct: $1,$1,$10,$10,$10,$10
Option 3 is correct: $1,$1,$20,$20
We have spent 58 out of 100 so we must get in return 42. Options are 3,4,5,6 bills. One of these is incorrect combination of bills. ---for 4 ->2 x $1 + 2 x $20---- ---for 5 ->2 x $1 + 1 x $20 + 2 x $10---- ---for 6 ->2 x $1 + 4 x $10---- and with only 3 bills Matthew cannot get $42 in change. Hence answer is 3.
the balance is $42... which means two of the bills will be $1 bills... this leaves us with $40... it's easy to figure out combinations that will give us this sum... (remember that we only have [n-2] possibilities remaining).
as the mathew has purchase only three items.it is obvious that he will get three bills
The change to be returned is 42$. The change can be in denomination of 20 or lesser and in all the sets of 3 notes, it is impossible to make an exact of 42$!
cost 58 , change = 42
6) 10 + 10 + 10 + 10+ 1 + 1
4) 20+ 20 + 1 + 1
5) 20 + 10 + 1 + 1
3 bills can never make $42 .
Why bother posting this
Matthew made a total purchase of $ 2 0 + $ 2 5 + $ 1 3 = $ 5 8
The teller was supposed to return him $ 1 0 0 − $ 5 8 = $ 4 2
Now, with the available denominations it is only possible to form $42 in three ways :
Any number of bills handed to Matthew other than 4, 6 or 10 will certainly be an incorrect change.
Hence, 3 and 5 are the incorrect changes (and correct answers).
Errata : Excuse my stupidity, 5 bills( $ 2 0 , $ 1 0 , $ 1 0 , $ 1 , $ 1 ) can also be a possibility.
Leaving 3 as the correct answer
As he purchased three items only, bill person at counter will give 3 bills only although he may give incorrect change
I think you misunderstood the question. Here, 'bills' mean the 'notes' themselves...
20+20+1=41 that is wrong so this is seller's option
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Total cost of items bought by Matthew = $58
Change that should have been given to Matthew = $42
If the change was correct, then the teller could give him 4, 5 or 6 bills.
$(20 + 10 + 10 + 1 + 1)= $42 (5 bills)
$(20 + 20 + 1 + 1) = $42 (4 bills)
$(1 + 1 + 5 + 5 + 10 + 20) = $42 (6 bills)
The question says that the change given was incorrect.
Therefore, the change given to him must not be $42.
Using 3 bills we cannot total up $42.
Hence , the possibility that the number of bills that the teller handed to Matthew is 3 .