Alex swims in a 400-m freestyle competition at an average speed of 1 1/3 m/s. If he increases his average speed to 1.6 m/s, how much less time will he take?

Question

This question is from the Singapore Primary Mathematics Workbook 6A.

Answer 1

Hi Quinn,

 

Recall the equation

d=rt

Distance = rates time time.

 

We have a single distance, 400m

We have two different rates 1 1/3 m/s and 1.6 m/s

 

Let's calculate the time for each rate

 

t = d/r

 

t = 400/(1 1/3) = 300 seconds

t = 400/1.6 = 250 seconds

 

By increasing his average speed, Alex will reduce his time by 

300-250 = 50 seconds.