The "Racing magic" takes 120 seconds to circle the racing track once.

Question

The "Racing magic" takes 120 seconds to circle the racing track once. The "Charging bull" makes 40 rounds of the track in an hour. If they left the starting point together, how many minutes will it take for them to meet at the starting point for the second time?

A. 3
B. 6
C. 9
D. 12
E. 15

A. 3
B. 6
C. 9
D. 12
E. 15

Skywalker18 · Answer

Time taken by Racing magic to make one circle = 120 seconds = 2 mins
Time taken by "Charging bull" to make one circle = 60 mins / 40 = 1.5 mins = 90 seconds
LCM of 90 and 120 seconds = 360 seconds = 6 mins
Time taken for them to meet at the starting point for the second time = 6 mins *2 = 12 mins

Answer D

FightToSurvive · Answer

The "Racing magic" takes 120 seconds to circle the racing track once. The "Charging bull" makes 40 rounds of the track in an hour. If they left the starting point
together, how many minutes will it take for them to meet at the starting point for the second time?

A. 3
B. 6
C. 9
D. 12
E. 15

Racing magic = 120 sec
Charging bull for 1 round = 60*60/40 = 90 sec
LCM of 90,120 = 360 sec = 6 mins.
Met for the second time after 6 mins as they met first time as they left together. B

hsbinfy · Answer

i concur to same xplanation but, the question asks when will they meet of 2nd time

1st time would indeed be answer choice B but for 2nd time it will be 12 min.

Correct Answer -D

mohshu · Answer

confused between B and D, anybody please provide explanation

CounterSniper · Answer

RM takes 120 seconds = 2 minutes to circle once 
Cb takes 60/40 = 1.5 minutes to circle once 
They will meet after the intervals of LCM (1.5 , 2.0) = 6,12,18..
thus they will meet for the second time at 12 minutes

tallyho_88 · Answer

the question says that they have started at the same time. which means that they have already met the first time. So, second time would be the next time they meet. i.e after 6 mins.

ligeraks · Answer

Confused as well. Would the fact that they started from the same point be considered as their first meeting or not? Anybody...?

rohitrawat9990 · Answer

120 sec= 2 min
=0.5 rev/min

40 rounds per hour
= 40/60 = 2/3 rounds per min

substitue the option

The minimum value at which both the above speeds give a whole number will be the second meeting as they have met first time at the starting point...

A. 0.5*3=1.5 reject
B. 6*.5 =3 
 6*2/3= 4

B is the correct answer

So after 6,12,18,24 the horses will meet

Sent from my iPhone using  GMAT Club Forum mobile app

DharLog · Answer

It is not concised question.
Why the first time they have met is not 0 sec ---> the second time 6 mins?

cbh · Answer

Yep, the question is not clear, doubt you gonna have smth confusing like that on real gmat or at least the question will be formulated differently
First time they meet when they start
second time in 6 mins
third time in 12 mins

Raksat · Answer

"Racing magic" = 120 seconds or say 2 minutes
The "Charging bull" makes 40 rounds of the track in an hour or say 3/2 minutes (60/40) to cover the track once.
so first time they will meet at starting point LCM (2,3/2) = 6 minutes
So second time they will meet at 12 minutes.
NOTE :  how to calculate LCM between 2 and 3/2  
 formula to find LCM between fractions :
LCM( (a/b) , (c/d) ) = LCM(a,c)/HCF(b,d) 
here LCM b/w 2 & 3 is 6
HCF b/w 1 and 2 is 1 
therefore LCM = 6

Nik11 · Answer

The questions provided by Bunuel are always extremely helpful in covering almost every concept that can be found on the GMAT. I agree with the fact that sometimes, as in this one, the question is slightly unclear, but what is important here is to understand the underlying concept/s and solve the question in an efficient way. You'll never find in the Quant a question that leaves room for doubts as this one so don't focus on this.

mimishyu · Answer

lets change all the number to the same unit better for us to compare
"racing magic" : 1 round, 120 sec=2 mins
"charging bull" : 40 rounds, 60mins = 1 round, 1.5 mins
if we want to know for which minute will they meet with each other, find the least common multiple to 
the number of 1.5 mins & 2mins
LCM(1.5, 2)=6
the first time they meet is at 6 mins, so we could infer the sec time is 12mins
ans(D)

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The "Racing magic" takes 120 seconds to circle the racing track once.

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The "Racing magic" takes 120 seconds to circle the racing track once.

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