Question

Justine swims freestyle at a pace of 150 laps per hour. Justine swims breaststroke 20 laps per hour slower than she swims butterfly. If Justine’s freestyle speed is three times faster than her butterfly speed, how fast does she swim breaststroke? Let b represent Justine’s butterfly speed in laps per hour and r represent Justine’s breaststroke speed in laps per hour.

Use tape diagrams to solve the problem.

Answer 1

Justine swims breaststroke at a pace of 50 laps per hour.

Explanation:

Consider the provided information.

Let b represent Justine’s butterfly speed in laps per hour and r represent Justine’s breaststroke speed in laps per hour.

Justine swims breaststroke 20 laps per hour slower than she swims butterfly.

This can be represented by tape diagrams as shown in figure 1.

Therefore, b=20+r

Justine swims freestyle at a pace of 150 laps per hour and Justine’s freestyle speed is three times faster than her butterfly speed,

This can be represented by tape diagrams as shown in figure 2.

Therefore, 3b=150

Simplify the above equation as shown:

3b=150

b=50

Hence, the Justine swims butterfly at a pace of 50 laps per hour.

Substitute the value of b in b=20+r

50=20+r

r=30

Hence, Justine swims breaststroke at a pace of 50 laps per hour.