P can give Q a start of 20 seconds in a kilometer race. P can give R a start of 200 meters in the same kilometer race. And Q can give R a start of 20 seconds in the same kilometer race. How long does P take to run the kilometer?
(1) 200 seconds
(2) 240 seconds
(3) 160 seconds
(4) 140 seconds
From the stem P gives R a start of 40 seconds or 200 m. i.e R takes 40 seconds to cover 200 m @ 5m/s.
So R takes 200 seconds to complete the race, as P gives R a start of 40 seconds he completes it in 200 - 40 = 160 seconds.