Ravi and Rajiv decided to run a 960 m long race on a track as long as the length of the race.

Which of the statement(s) below is (are) sufficient to conclude that Rajiv ran at a speed of 10 m/s?

Statement 1: Ravi is allowed to start 5 seconds before Rajiv started running.

Statement 2: Ravi ran at 8 m per second.

Statement 3: Rajiv caught up with Ravi with $$\frac{3}{8}$$​ of the track length still to be covered.

Correct option is A

Given:

The race track length is 960 m.
Statement 1: Ravi is allowed to start 5 seconds before Rajiv started running.
Statement 2: Ravi ran at 8 m per second.
Statement 3: Rajiv caught up with Ravi with $$\frac{3}{8}$$​​​ of the track length still to be covered.

Formula Used:

Distance = Speed $$\times$$ Time

Solution:

From Statement I and II:

Relative Distance = 8 $$\times$$ 5 = 40 meter

From Statement III:

=> 1 - $$\frac{3}{8}$$ = $$\frac{5}{8}$$ Track still to be covered.​

Rajiv caught up with Ravi at $$\frac{5}{8}$$ $$\times$$ 960 = 600 meter

Time after which Ravi is caught = $$\frac{600 - 40}{8} = 70$$ second

So, Speed of Rajiv = $$\frac{600}{70}$$ = $$\frac{60}{7}$$ Meter/Second

Thus, there is no combinations of statements which shows that speed of Rajiv is 10 m/sec.

So, the correct answer is (a) Even all the three statements taken together is not sufficient.