Answer : Option D

Explanation :

While A runs 100 m, B runs (100-10)=90 m and C runs (100-13)=87 m
i.e., when B runs 90 m, C runs 87 m
$MF#%\text{=> when B runs 180 m, C runs }\dfrac{87}{90} \times 180 \text{= 174 m}$MF#%
Hence, in a 180 m race, B will beat C by (180-174)=6 m

Clearly, B covers 28 m in 7 seconds.
B's time over the course = (7/28 x 1000) sec = 250 seconds.
A's time over the course = (250 - 7) sec
= 243 sec = 4 min. 3 sec.

While A covers 1000 m, B covers (1000 - 40) m = 960 m
And C Covers (1000 - 64) m or 936 m
When B covers 960 m, C covers 936 m
When B cover 1000 m, C cover (936/960 x 1000) m =975
binduB can give C a start of (1000-975) or 25 m

Answer : Option D

Explanation :

In 100 m race, A covers the distance in 36 seconds and B in 45 seconds.
Clearly, A beats B by (45-36)=9 seconds
$MF#%\text{Speed of B = }\dfrac{\text{Distance}}{\text{Time}} = \dfrac{100}{45}\text{ m/s}\\\\ \text{Distance Covered by B in 9 seconds = Speed × Time = }\dfrac{100}{45} \times 9\text{ = 20 metre}$MF#%
i.e., A beats B by 20 metre

A's speed = 5 x 5 m/sec = 25 m/sec. 18 18

Time taken by A to cover 100 m = 100 x 18 sec = 72 sec. 25

Time taken by B to cover 92 m = (72 + 8) = 80 sec.

B's speed = 92 x 18 kmph = 4.14 kmph. 80 5

Answer : Option B

Explanation :

When A covers 100 m, B covers (100-25)=75 m
When B covers 100 m, C covers (100-4)=96 m
$MF#%\text{=> When B covers 75 metre, C covers }\dfrac{96}{100}\times 75 = 72\text{ m}$MF#%
i.e., When A covers 100 m, B covers 75 m and C covers 72 m
=> In a 100 m race, A beat C by (100-72)=28 m

A : B = 100 : 75

B : C = 100 : 96.

A : C = A x B = 100 x 100 = 100 = 100 : 72. B C 75 96 72

A beats C by (100 - 72) m = 28 m.

A : B = 100 : 90.

A : C = 100 : 87.

B = B x A = 90 x 100 = 30 . C A C 100 87 29

When B runs 30 m, C runs 29 m.

When B runs 180 m, C runs 29 x 180 m = 174 m. 30

B beats C by (180 - 174) m = 6 m.

B runs 35 m in 7 sec.

B covers 200 m in 7 x 200 = 40 sec. 35

B's time over the course = 40 sec.

A's time over the course (40 - 7) sec = 33 sec.

A : B = 100 : 90.

A : C = 100 : 72.

B : C = B x A = 90 x 100 = 90 . A C 100 72 72

When B runs 90 m, C runs 72 m.

When B runs 100 m, C runs 72 x 100 m = 80 m. 90

B can give C 20 m.