Is the average speed of a man more than 64 kmph ?
I. the man covered the whole journey in three stretches.
The average speed for the first two stretches was 60 kmph.

Options

A. only I statement is sufficient but second is not
B. If the question can be answered using either statement alone.
C. If the questions can be answered using I and II together but not using I or II alone
D. If the question cannot be answered even using I and II together.

Answer

C

Explanation

Neither of the statements is independenty sufficient as the distances covered in three.
stretches and the speed are given in different statements.
Combining both the statements let the distance covarad in the third stratch be d/4 km.
Then in first two stretches it is3d/4 km.
`:.` Average sped is `(3d//7+d//4)/((3d//4)/(60))+(d//4)/((d//4)/(8))=64 "kpmh"`
The maximum average spedd will occure if the entire last stretch is maximum in length
`i.e, (d)/(4)` km and is travelled at the maximum speed i.e., 80 kmph.
`:.` We can say that the average speed will be at most 64 kmph