Question

15. At a railroad station there are two tracks, A and B, with the trains going to the city. At 7
A.M. a train leaves on each track, at the same time, for the city. From then on, the trains on
frack A leave every 8 minutes, and those on track B leave every 9 minutes. Mrs. Cortez
arrives at the station at 8:25 A.M. and may take either train. How many minutes will she
have to wait for the next train going to the city?

A. 2

B. 3

C. 4

D.5​

Answer 1

Answer:

3 minutes.

Step-by-step explanation:

Starting at 7 A.M, trains leave at 8 minutes interval in track A and at 9 minutes interval in track B.  

Mrs. Cortez arrive a station at 8:25 A.M.

So, the gap of time is 1 hour and 25 minutes i.e. 85 minutes.  

Hence, for track A, the nearest multiple of 8 minutes which is more than 85 minutes is 88 minutes.

Therefore, Mrs. Cortez has to wait (88-85)=3 minutes more to get a train in track A.

Again for track B, the nearest multiple of 9 minutes which is more than 85 minutes is 90 minutes.

Therefore, Mrs. Cortez has to wait (90-85)=5 minutes more to get a train in track A.

So, she has to wait for a minimum of 3 minutes for the next train going to the city. (Answer)