Question

Avik starts running on a circular track of length 600 metres. He completes the first round in 2 min 24 sec. For all subsequent rounds, his speed decreases by 10% of his prehous round's spe
speed when he is running the third round?
Pick ONE option
A) 12.15 km/hr
B) 20.25 km/hr
C) 14.58 km/hr
D) 16.2 km/hr​

Answer 1

Answer:

t = 2 min 24 = 2+24/60 min = 2+2/5 min = 12/5 min = 12/(5×60) = 1/25 h

d = 600 m = 600/1000 km = 3/5 km

speed = 3/5 ÷ 1/25 km/h = 3×25/5 km/h = 15 km/h

at the third round his speed =

$15 \times \frac{90}{100} \times \frac{90}{100}$

$= 15 \times0 .81 = 12.15 \: \frac{km}{h}$

Answer 2

Given :

Length of the circular track = 600 m

Time taken to complete first round = 2 min 24 sec = 144 sec

To find :

Speed of Avik in third round .

Solution :

Speed of Avik in the first round = 600 m / 144 s

=> Speed of Avik in km/h = ( 600 / 144 ) * ( 18 / 5 ) km/h

=> Speed of Avik = 15 km / h

Speed of Avik in third round = 15 * ( 90 / 100 ) * ( 90 / 100 )

=> Speed of Avik in the third round = 12.15 km/h

Speed of Avik in the third round is 12.15 km/h .