Question

A person covers first half of the distance with 6 m/s and rest half of the distance is covered with 9 m/s and 15 m/s in two equal time intervals. Find average speed of the journey.

(1) 12 m/s 

(2) 9 m/s 

(3) 10 m/s 

(4) 8 m/s

Answer 1

Correct Option is (4) 8 m/s 

Average speed in second half distance = \(\frac{9+15}{2}= 12\) m/s

Average speed of journey = \(\frac{2d}{\frac{d}{6}+\frac{d}{12}}=\) 8 m/s