Answer: 15 seconds
It would have taken 20 seconds at 1/20 per second, but it is 3/4 of that. 3/4 of 20 is 15.
Step-by-step explanation: In case you need mathematical proof
Distance= speed times time
To find the speed, take the given distance divided by the given time:
is the speed
The whole distance is 1. We need to solve for time.
D = s×t
1 =
× t Multiply both sides by 3/4 (cancels 3/4 on right side)
3/4 × 1 = 1/20 × t Multiply both sides by 20 (cancels 1/20 on the right side)
20 × 3/4 = t 3*20/4 = 60/4 = 15
15 = t