Discussion of Question with ID = 021 under Boats-and-Streams

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Question

The speed of a steamer in still water, the upstream speed of the steamer and the downstream speed of the steamer form an A.P.(Arithmetic Progression) whose common difference is \${4/9}\$. What is the speed of the river?

A

\${4/9}\$ units.

B

\$1{5/8}\$ units.

C

2 units.

D

\$2{9/11}\$ units.

Soln.
Ans: a

Let the speed of the steamer in still water be u and the speed of the river be v. The three speeds are u - v, u and u + v. They are in an A.P. with a common difference equal to v. Since v is also the speed of the river, the required answer is: \${4/9}\$.