Cities A and B are in different time zones. A is located 3000 km east of B. The table below describes the schedule of an airline operating non-stop flights between A and B. All the times indicated are local and on the same day.

Assume that planes cruise at the same speed in both directions.

However, the effective speed is influenced by a steady wind blowing from east to west at 50 kmph.

Q: What is the plane’s cruising speed in kmph?

a. 700

b. 550

c. 600

d. 500

e. can not be determined

Departure |
Arrival |
||

City |
Time |
City |
Time |

B |
8:00 am |
A |
3:00 pm |

A |
4:00 pm |
B |
8:00 pm |

Let
the speed of the plane be p Kmph.

So the speed of plane from A to B will be 'p+50' and the speed from B to A will
be 'p-50".

We notice that the plane goes from B to A stays there for 1 hr
and again come back to B with total time duration 12 hrs.

So we have {3000/(p-50)}+1+{3000 /(p+50)}= 12.

On substituting the options, we can clearly see that speed of the plane is 550
which satisfies the above equation.

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