Question

A and B start at the same time from P and Q (55 km apart) to Q and P at 3 and $2\frac{1}{2}$ km/h respectively. They meet at R and then reach Q and P to return immediately and meet again at S. The distance from R to S is:

• A. 10 km
• B. 12 km
• C. 15 km
• D. 16 km

Answer 1

The correct option is A 10 km


Here, relative speed will be = 5.5 km/h
First meeting point is 'R'.
That is, $=\frac{55}{5.5km/h}=10h$
That means PR = 30 km, and QR = 25 km
Second meeting point is 'S' = $\frac{165}{5.5}=30h$
Total distance travelled by A for second meet: 3 x 30 = 90 km, which means A will be 35 km away from Q.
That is, RS = SQ - RQ = 35 - 25 = 10 km