Tourists And Buses

Algebra Level 3

A group of tourists are traveling in several buses, each with a maximum capacity of 32 32 passengers.

If there are 22 22 tourists in each bus, then one tourist would not have a seat. If one bus isn't used, then each bus can hold an equal number of tourists and accommodate all of them.

If t t is the number of tourists who are going to travel and there are b b buses available, what is the value of t + b t+b ?

Details and assumptions

  1. The presences of the bus drivers are ignored.
  2. The values of t t and b b are the original numbers of tourists and buses.


The answer is 553.

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24 solutions

Sally Allam
Jan 15, 2014

If there are 22 tourists in each bus, then one tourist would not have a seat.

If one bus isn't used, then there would be 23 tourists haven't a seat, and each bus can hold an equal number of tourists and accommodate all of them. So we could divide 23 on (b -1) (buses except one).

23 is a primary number, which can't be divide except on 1 or itself. (b -1) couldn't be one bus, because (22 tourists on it + 23 tourists haven't seats = more than the maximum capacity of it 32). So (b - 1) should be 23, there is no answer else.

b - 1 = 23

then, b = 24 buses

Now... to get t, we have to solve the equation: t = tourists in each bus \times b

There are two ways to solve this equation, which are: 1) "If there are 22 tourists in each bus, then one tourist would not have a seat." 2) "If one bus isn't used, then each bus can hold an equal number of tourists and accommodate all of them."

1) Means: t - 1 = 22 \times b = 22 \times 24 = 528 Then, t = 529

2) Means: t = 23 \times (b - 1) = 23 \times 23 = 529 Here... notice that: tourists in each bus would be 23, because they were 22, and when we deleted a bus, there would be 22 lost their bus, in addition to the tourist which hadn't a seat firstly. So this means: 23 tourists haven't a seat, and 23 buses have in each one 22 tourists, so each bus from the 23 buses should host one tourist which haven't seat,

finally it would reaches to 23 buses with 23 tourists in each bus.

So.. wow.. the finally step ッ

t + b = 529 + 24 = 553

553 is the correct solution

CONGRATS,
              you've been reached  (❀◕‿◕)

I WAS UNABLE TO FOLLOW 2ND PART

biswabhusan Das - 7 years, 4 months ago

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You knew that we have 24 buses, from first part.

22 tourists in each bus, and one tourist haven't a seat.

22 tourists X 24 buses = 528
(that's all tourists in buses, except one haven't a seat)

t - 1 = 528,
t = 529

Sorry if it was complex. I hope this will be much easier ^^

Sally Allam - 7 years, 4 months ago

If there are 2 buses and 45 tourists then also all the conditions will be satisfy. then answer will be 47. what is your comment???????????????

Omkar Tiwari - 7 years, 4 months ago

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You need to form an equation.. Number of buses= x Therefore the initial tourists are 22x Therefore the total number of tourists are 22x +1 But then the buses are decreased by one,so the number of buses= x-1 Passengers not having a seat=1 So according to the data... (22x / x) - (22x+1 / x-1) = 1 On solving,you will get x =24 So the number of buses=24 Tourists=22(24) + 1 =529 On adding you will get 553 as the answer.. :-) Hope it helped !

Parth Viradia - 7 years, 4 months ago

No, there is a maximum of 35 tourists in each bus. In your solution, if one bus is removed, all 47 must go into one remaining bus which is not possible.

Tong Choo - 7 years, 4 months ago

max no of tourists = 32

Anand Raj - 7 years, 4 months ago

you forgot about 32 maximum passengers :p

Md. Mohaiminul Islam - 7 years, 3 months ago

hum

Ritesh Chaudhari - 7 years, 4 months ago

The number of tourists can be written as 22 b + 1 22b + 1

As there is an equal number of tourists in each bus if 1 less bus is used,

22 b + 1 0 ( m o d b 1 ) 22b +1 \equiv 0 \pmod{b-1}

22 b 22 + 23 0 ( m o d b 1 ) 22b -22 + 23 \equiv 0 \pmod{b-1}

23 0 ( m o d b 1 ) 23 \equiv 0 \pmod{b-1} , b 1 b-1 is a multiple of 23.

At 24 buses, there are 529 passengers. t + b = 553 t + b = \boxed{553}

i appreciate this different approach.

Krishna Rohit - 7 years, 4 months ago

Clean and Smart! Nothing better using number theory for these kinds of algebraic problems!

VENKATA VIVEK GOWRIPEDDI - 7 years, 4 months ago

b - 1 is not a multiple of 23. 23 is a multiple of b - 1. Since 23 is prime, the only factors are 23 or 1. Therefore, b - 1 = 1 or 23. But b - 1 = 1 is not a solution since it will end up putting 47 people in one bus which exceeds the limit.

Tong Choo - 7 years, 4 months ago

i confused of that mod

Valerian Pratama - 7 years, 4 months ago

Great solution, Nucky!

Vincent Tandya - 7 years, 4 months ago

http://www.artofproblemsolving.com/Resources/Papers/SatoNT.pdf............This document contains basic stuff about number theory.......Number Theory opens doors to a whole new way of thinking and problem solving. Very helpful for High school and 1st/2nd year college students.

VENKATA VIVEK GOWRIPEDDI - 7 years, 4 months ago

nice approach...

Vighnesh Raut - 7 years, 2 months ago
Thanic Samin
Jan 16, 2014

Assume that in the second case, the passenger number in each bus is k.So, we get 2 equations.

22b+1=t

t=kb-k.

Writing the value of t in the first equation, we get,

22b+1=kb-k

kb-22b=k+1

b(k-22)=k+1

b = k + 1 k 22 b=\frac{k+1}{k-22}

Thus b is a whole number, the denominator is 1.

So k-22=1, and k=23.

So b = 23 + 1 23 22 b=\frac{23+1}{23-22} =24

So t=23 × \times 24-23=529.

So the answer is 529+24= 553 \boxed{553}

excellent answer samin what about your profession ?

Harishkumar Sarvepalli - 7 years, 4 months ago

nice

Muhammad Tayyab - 7 years, 4 months ago

Good Answer..:)

Yashada kolatkar - 7 years, 4 months ago

Imagine that there are b buses with 22 tourists per bus. And there is one lone tourist that is outside. Removing the last bus, the tourists that are outside will be

22 + 1 = 23 22 + 1 = 23

According to the problem, these 23 passengers can be equally divided onto the remaining buses. Therefore we can say that the remaining buses are 23. Adding the last one would total up to 24 buses. Thus,

t = 22 b + 1 t = 22b + 1

t = 22 ( 24 ) + 1 t = 22(24) + 1

t = 528 + 1 t = 528 + 1 t = 529 t = 529

t + b = 529 + 24 = 553 t + b = 529 + 24 = \boxed{553}

I have to say that I didn't think of that. Excellent one, Nikko :)

Vincent Tandya - 7 years, 4 months ago

I THINK YOUR SOLUTION IS BEST

ASHISH KUMAR - 7 years, 4 months ago

nice soln

Madhu Mangal Kumar - 7 years, 4 months ago

amazing.....

Vighnesh Raut - 7 years, 2 months ago

When we take away one bus we will need to accommodate its 22 tourists on all buses plus the one tourist= 23 tourists. As 23 is a prime number it will be divided only by itself! so we need 23 buses to accommodate the 23 tourists. Which means we should have had 24 buses in order to have 23 left after taking one bus away. 24x22= 528, 528+1= 529, 529/23= 23, t+b= 24+529= 553.

well done (y)

Fareeha Khalid - 7 years, 4 months ago

nice soln..

Rahul Pandey - 7 years, 4 months ago
Pj Singh
Jan 15, 2014

After not using one bus, no. of tourist left without a bus = 23 (22 from the bus + 1 without a bus) Those 23 must have been distributes one each on remaining buses, one each bus. 23 is a prime no. Thus the no. of tourist is 23x23 and no of buses =23 used + 1 empty t+b= 23x23 + 24

U r explaination is amazing shortest and best I salute u.

Pritesh Nile - 7 years, 4 months ago

If there are 2 buses and 45 tourists then also all the conditions will satisfy. then answer will be 47. what is your comment???????????????

Omkar Tiwari - 7 years, 4 months ago
Bharat Karmarkar
Jan 15, 2014

From the given condition, t = 22b + 1. Now, 22b + 1 should be divisible by b - 1 and the quotient must be less than 32. Make 22b + 1 as 22(b-1) + 23. This should be divisible by b -1 means 23 should be divisible by b -1. This means b - 1 must be 1 or 23. If it is 1, the quotient exceeds 32. So, b -1 is 23. This gives b = 24 and then t = 529. Thus we get t + b = 553. I enjoyed this problem!!

William Cui
Jan 16, 2014

We have the two equations:

22 b = t 1 22b=t-1 x ( b 1 ) = t x(b-1)=t

where x x is equal to the equal number of tourists on the bus.

Substituting x ( b 1 ) x(b-1) as t t into the first equation, we have

22 b = x ( b 1 ) 1 22b=x(b-1)-1

22 b = b x x 1 \implies 22b=bx-x-1

b x 22 b = x + 1 \implies bx-22b=x+1

b × ( x 22 ) = x + 1 \implies b\times (x-22) = x+1

where x x is an integer and 22 < x 32 22 < x \le 32 .

We also must have x 22 x-22 be a divisor of x + 1 x+1 , since b b must be an integer.

The only value of x x that satisfies all conditions is 23 23 , so we have x = 23 x=23 . This gives b = x + 1 = 24 b=x+1=24 and t = 23 × 23 = 529 t=23\times23=529 , giving t + b = 24 + 529 = 553 t+b=24+529=\boxed{553}\ \blacksquare .

Also, Vincent Tandya = VincentTandya from AoPS?

William Cui - 7 years, 4 months ago

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Yes.

Jason Sebastian - 7 years, 4 months ago

Yep.

Vincent Tandya - 7 years, 4 months ago

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yay hi

William Cui - 7 years, 4 months ago

yay hi

William Cui - 7 years, 4 months ago

Neatly written, good one William :)

Vincent Tandya - 7 years, 4 months ago
Bruno Nishimoto
Jan 15, 2014

"If there are 22 22 tourists in each bus, then one tourist would not have a seat", it means that: t = 22 b + 1 t=22b+1

"If one bus isn't used, then each bus can hold an equal number of tourists and accommodate all of them", it means that: t = ( b 1 ) × k t=(b-1)\times k , where k 32 k\leq 32

So we have: 22 b + 1 = k ( b 1 ) 22 b + 1 = k b k k + 1 = b ( k 22 ) 22b+1=k(b-1)\Longrightarrow 22b+1=kb-k\Longrightarrow k+1=b(k-22)

Analysing ( m o d k 22 ) \pmod {k-22} we have: k + 1 0 ( m o d k 22 ) 23 0 ( m o d k 22 ) k+1\equiv 0\pmod{k-22}\Longrightarrow 23\equiv0\pmod{k-22} (since k 22 ( m o d k 22 ) k\equiv22\pmod {k-22} ).

So, k 22 = 23 k-22=23 or k 22 = 1 k-22=1 , but in the first option, k > 32 k>32 , absurd!!! So k = 23 k=23

And then, b = 24 b=24 and t = 529 t=529 , so b + t = 553 b+t=553

Rajnish Bharti
Jan 15, 2014
  1. 22*b + 1 = t
  2. (b-1)* X = t where X = equal number of tourists
  3. 22 < X <=32
  4. b = (1+X)/(X-22)
  5. You need to find b (an integer) based on condition 3.
Abin Das
Jul 13, 2014

Suppose there are n buses.

Then there must be ((22*n)+1) tourists.

Also,if n-1 buses are used, then equal number of tourists will be present in each bus,i.e (no. of tourists)/(n-1) is a whole number.

Thus, (22n+1)/n-1 is a whole no.,W.

Let m=n-1.i.e n=m+1.

Thus the equation becomes

(22*(m+1)+1)/m=W

(22m+22+1)/m=W

22+23/m=W

Thus m=23 or 1 for W to be a whole no.

i.e n=24 or 2

If n=2,no.of tourists=45

i.e if one bus is left unused,then 45 tourists will travel in a single bus.This is not possible as maximum capacity of a bus is 32 tourists.

Thus n=24 and no.of tourists = 22*24 +1=529

Thus,t+b=24+529=553

22b + 1= t ............A
t/(b-1) = integer.
(22b + 1)/(b-1) = integer.
(22b -22 +23) (b-1) = integer
{(22b -22 )+23}/ (b-1) = integer
(22b -22 )/ (b-1) + 23/ (b-1) = integer
22 + 23/ (b-1) = integer.
23/ (b-1) = integer
only b= 24 can satisfy A.
t= 22 x 24 +1 = 529
b + t = 553









let say total buses is B

total tourists is T = 22 B + 1

then reduced one bus, so now total buses is B -1.

and number of tourists per bus = (22B + 1)/(B-1) = 22 + n where 1 <= n <= 10

then we'll have :

B = 23/n + 1

B will be integer if and only if n = 1

so, B = 24

T + B = 22 * 24 + 1 +24 = 553

Oon Wei Yi
Jan 27, 2014

"If there are tourists in each bus, then one tourist would not have a seat."

From this, we get 22b + 1 = t

"If one bus isn't used, then each bus can hold an equal number of tourists and accommodate all of them."

Let x = accommodated equal number of tourists when one bus isn't used

Therefore, x≦32 . Also, x(b-1) = t

Equating both equations, we get

22b + 1 = x(b-1)

b = (x+1)/(x-22)

Since b must be a whole number, (x+1)/(x-22) must also be a whole number.

To make (x+1)/(x-22) a whole number, the denominator may be = 1.

If x-22 = 1 , then x=23 (satisfying x≦32)

Hence, substituting x=23 , into the equations above, we get b=24 and t=529 .

Fianlly, b+t = 553

Lucky Ducky
Jan 24, 2014

"each with a maximum capacity of 32 passengers" , and "If there are 22 tourists in each bus, then one tourist would not have a seat" , so:

22b+1=t (b,t∈N*) <=>b=(t-1)/22

and t<32b (#)

"If one bus isn't used, then each bus can hold an equal number of tourists and accommodate all of them" , so:

t=n(b-1) (n∈N*)

=> 22b+1=n(b-1)

=> b(n-22)=n+1

n=22 => impossible

n><22 => b=(n+1)/(n-22)=(n-22+23)/(n-22)=1+23/(n-22)

b∈N*=> n-22=23 or n-22=1 <=> n=45 or n=23 <=> b=2 (impossible (#) ) or b=24

=> (b;t)=(24;529)

=> *b+t=553 *

Ashish Kumar
Jan 22, 2014
  • 22b + 1 = t
  • t mod b-1 = 0 => (22(b-1) + 23) mod b-1 = 0 => 23 mod b-1 = 0 => as 23 is prime number, only possible value of b = 24

  • Dont know why 32 value is given for

Joe Ashour
Jan 18, 2014

from the first relation we get : t=22b+1 and from the second we get : b-1=t/b-1 by solving the two equations we get b=24 and t=529

Suresh Chowdary
Jan 18, 2014

22b+1=t; (b-1)23=t; b=24; t=529; t+b=553

Ravi Shankar
Jan 18, 2014

t=22b+1.
If one bus is evacuated, there will be now 23 tourist left. Now we have to equally distribute 23 tourist in remaining b-1 buses. This is possible if the number of bus left is either 1 or 23 (1 can not be true as no. of tourist accommodated (45) will exceed as max capacity i.e 32 ). Hence total no of buses will be 24. and total no. of tourist will be 529.

Shibin Kuriakose
Jan 17, 2014

t is one more than 22's multiple ---------> t = 22b+1

now if in 2nd case there are n tourists per bus,

t = n(b-1)

equating both we get

b(n-22) = n+1

Now we know three things

a) The number of tourists and buses are integers :P

b)The maximum value of n is 32

c) n has to be greater than 22 ( see above equation) - b has to be positive and an integer trying numbers from 23 to 32 we find 23 is the value of n

and hence b=23+1=24

and t = 22x24+1 = 529

∴ t+b=553

:) good day! hope you understood !

Rahul Khanna
Jan 16, 2014

equations:

22n + 1 = Passengers x(n-1) = Passengers

22n + 1/n-1 = Integer 22n + 23 - 22/n-1 = Integer 22(n-1) + 23/n-1 = Integer n=24 (smallest)

therefore : no. of passengers + buses = 22n + 1 + n =553

Leslie Brenes
Jan 16, 2014

For a long time, I felt wonderful while solving this. So, you have a number of tourists, call that "t", and you know that the exact number of buses, call it "b", contains 22 tourists however, 1 passenger doesn't has a seat so, here's the math: t=22b+1 now, you don't know the value of "b", but you know that the number of buses minus 1 gives you an exact of 23 because that one bus contained 22 passengers: b-1=23 the rest is easy: b=23+1=24 b=24 t=22 \times 24 +1 t=529 t+b=529+24=553. :)

Sagar Pohekar
Jan 15, 2014

at start if we consider that buses are running with their full capacity then the total no of passenger will be t=32 b but this is not the case,if there are 22 passengers in each bus then 1 would not get seat so no of passengers will be t-1=22 b now if 1 bus isn't used then all passengers can be accommodated equally in all remaining buses (b-1) as passengers are equally accommodated therefore t/(b-1)=(b-1) .i.e (22 b+1)/(b-1)=(b-1) solving this we'll get b=24 t=22 b+1 =529 if b-1 buses are used then t/(b-1)=529/23=23=(b-1) hence this is the solution t=529 b=24 t+b=553

Rishi Ranjan
Jan 15, 2014

22b+1=t. => 22(b-1)+23=t =>b-1=23 as (b-1)|22(b-1)+23 so b-1=23=>b=24, t=529. b+t=553

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