CAT Practice : Speed Time, Races

If you can calculate how long does P take to cover 500m, you are almost there!

Dead Heat

    Q.14: P cycles at a speed of 4 m/s for the first 8 seconds, 5 m/s for the next 8 seconds, 6 m/s for the next 8 and so on. Q cycles at a constant speed of 6.5 m/s throughout. If P and Q had to cycle for a 400 m race, how much lead in terms of distance, can P give Q and still finish at the same time as Q?
    1. 43.4 m
    2. 56.6 m
    3. 32.1 m
    4. P cannot give a lead as Q is always ahead of P

 

  • Correct Answer
    Choice C. 32.1 m

Detailed Solution

Distance covered by P in 8 sec = 4 * 8 = 32 m
Distance covered by P in 16 sec = 32 + 5 *8 = 72 m
Distance covered by P in 24 sec = 72 + 6 * 8 = 120 m
Distance covered by P in 32 sec = 120 + 7 * 8 = 176 m
Distance covered by P in 40 sec = 176 + 8 * 8 = 240 m
Distance covered by P in 48 sec = 240 + 9 * 8 = 312 m
Total distance in 48 sec = 312m
To cover balance 86 m with speed = 10 m/sec, time taken = 86/10 = 8.6 sec
So P would finish 400 m in 48 + 8.6 = 56.6 seconds.

In 56.6 seconds, Q cycles 56.6 * 6.5 = 367.9 m or B should have a 32.1 m lead to result in a dead heat.

Correct Answer: 32.1 meters



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"Life is a race ... if you don't run fast ... you will be like a broken undaa" - Veerusahasra Buddhi