11. in a 200 m race, P beats Q by 75 m and Q beats
R by 40 m. R finished the race 5 seconds after
Q finished. Find
(i) the speed of each person.
(ii) the distance by which P beats R.
Answers
1. In a race of 1000m, A beats B by 50m or 5 seconds.
Time is taken by A to complete the race
Sol: Since A beats B by 50m. It means by the time A reaches the winning point, B is 50 m away and as A beats B by 5 seconds, it means B takes another 5 seconds to reach the winning point. This means B covers 50m in 5 seconds i.e., B’s speed is 50/5 = 10m/s. Since A wins by 50m, in the time A covers 1000m, B covers 950m in 95 seconds (950/10). Hence A will take 95 seconds to cover 1000m.
Therefore, A’s speed is 1000/95= 10 10/19 m/sec.
In this question, we firstly find the speed of B by analyzing the distance it cover within the given time, then within the same time A had covered 1000m. By this we get the speed of A too.
Answer:
(1) P-16,Q-10,R-8
(2) 100 m