Petr and Jon are playing a guessing game. Petr thinks of 2 integers ( a , b ) , each of which are from 0 to 10, and tells Jon their product. If Petr says that the product is 24, how many distinct ordered pairs of integers could Petr be thinking of?
This problem is posed by Anderson A .
Details and assumptions
For an ordered pair of integers ( a , b ) , the order of the integers matter. The ordered pair ( 1 , 2 ) is different from the ordered pair ( 2 , 1 ) .
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
Genius
Don't miss out ( 1 × 2 4 ) in the pairs,though it is not required here.
1x24 2x12 3x8 4x6
oh yeah missed that
24 is the multple of 2,3,4,6,8 which r d integers between 0 to 10..now of these nmbrs,(3,8),(4,6),(6,4),(8,3) this pair of nmbrs cmplts d givn cndtion..the ans is 4 pair of integers cmplts d condition
We find the number of ordered pairs of factors from 0 to 10. We find these: ( 3 , 8 ) ( 4 , 6 ) ( 6 , 4 ) ( 8 , 3 ) The answer is 4 .
Why are these all the pairs? Did you have to look at all the 100 possible products?
Log in to reply
I found factors of 24: (1,24), (2,12), (3,8), (4,6), and the reverses.
Only these four have both factors below 10.
Is this factoring? :D
First, reach the factor of 2 4 , that is; 2 , 3 , 4 , 6 , 8 , 1 2 , 2 4
Because the integers that thought by Petr is between 0 to 1 0 , and the product of them is 2 4 .
So the number, and its possible ''structure'' is: 3 , 8 4 , 6 6 , 4 8 , 3
There is 4 possible
I did this with permutations. Total ordered pairs = 3 ! 1 ! 4 !
Log in to reply
I'm not too sure how you did it with permutations. Just because you got the correct numerical answer doesn't mean that the logic was correct.
Your formula looks like the combination ( 1 4 ) , in which case you are choosing one value of 3 , 4 , 6 , 8 , and the other one is fixed. However, you need to justify why the rest do not work.
why not 1*24
There are 4 combinations of 2 numbers whose product is 24 from 0 to 10 , ie. (3,8) , (8,3), (4,6) and (6,4).
It can be 3x8, 8x3, 6x4 or 4x6
is it Petr or Jon who is thinking this numbers....
Since it is given that integers are from 0-10 then possible product of integers are 8 3 and 6 4.But distinct ordered possible pair of integers are - (3),(4),(6),(8) so correct answer is 4 if you count it.Here 83 and 64 means product of 8,3 and 6,4
24= 8 * 3 = 6 * 4
( 8 , 3 ) , ( 3 , 8 ) , ( 6 , 4 ) , ( 4 , 6 )
The factors of 24 are 1,2,3,4,6,8,12,24. Now, we can see that the ordered pairs satisfying this are (1,24),(24,1),(2,12),(12,2),(3,8),(8,3),(4,6) and (6,4).
But, it is also said that for the ordered pair (a,b), we have a and b can range from 0 to 10. So, the ordered pairs (1,24),(24,1),(2,12) and (12,2) does not satisfy this. So, these pairs does not belong in the solution set.
Only 4 ordered pairs, i.e, (3,8),(8,3),(6,4) and (4,6) belong in the solution set, so no. of required ordered pairs = 4
integers r frm 0 to 10.... so 24 is our product\ possible factors are 8 3 or 4 6... then (4,6),(8,3)...total 4 integers! Ans= 4
The answer is =(3 x 8),(4 x 6) = (8 x 3),(6 x 4) = These are the 4 pairs whose product is 24.{between 0 to 10}
In between 0 and 10, there is only possible to take 8,3 and 4.6 pairs for the product 24. If we interchange we get 4 pairs. i.e., (8,3), (4,6), (3,8), (6,4).
Problem Loading...
Note Loading...
Set Loading...
Let's take out the prime factors of the given number 2 4 , which are 2 × 2 × 2 × 3 . These can be arranged in the forms of pairs-
2 × 1 2 , 3 × 8 and 4 × 6 .
But we have to choose pairs which have numbers between 0 and 1 0 .
Thus, we get only two pairs- 3 × 8 and 4 × 6 .
Since this question asks for the number of ordered pairs, we can form two more pairs from these two pairs, giving us a total of 4 pairs.