SSC CGL 2022 PYQ — Question 60

The correct answer is Option 1 i.e. ${{17} \over 3}m/sec$

In the 1200m race, A beats B by 100m

In the 600m race, B beat C by 100m.

In the 720m race, A beat C by 30 sec.

If the distance is the same, S₁T₁ = S₂T₂

And if the time is the same, ${D_1 \over D_2} = {S_2 \over S_1}$

⇒Since A beat B by 100m, the ratio of speeds of A and B = 1200 : 1100 = 12 : 11

⇒Also, B beat C by 100m,  ratio of s the eds of B and C = 600 : 500 = 6 : 5

⇒Now, the ratio of speeds of A, B , and C = 72 : 66 : 55 for same time.

⇒The ratio of time taken by A, B, and C = 55 : 66 : 72

⇒So, given that A beat C by 30 sec, i.e. (72 - 55) = 17 → 30

⇒In a 720 m race, Time taken by C = ${30 \over 17 } \times 72$

⇒Now, the speed of C = $720 \over {30 \over 17} \times 72$ = 17/3.

Hence the speed of C is 17/3 m/sec.