Advertisement

### 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: ${4/9}$.