Question

Alex drives at an average speed that is 3/4 of the average speed that Roy's train travels. Alex takes 40 minutes to travel 65 km in her car. Roy travels for 1 hour and 15 minutes on his train. How far does Roy travel to 2 dp?

Answer 1

162.50 km

Explanation:

Alex: 40 minutes for 65 km

speed = distance/time = (65 km)/(40 min) * (60 min)/(1 hr) = 97.5 km/h

Alex's speed = 3/4 of Roy's speed

Roy's speed = (Alex's speed)/(3/4) = (97.5 km/h)/(0.75) = 130 km/h

speed = distance/time

distance = speed * time

time = 1 hour + 15 minutes = 1 hour + 15/60 hour = 1.25 hour

distance = 130 km/h * 1.25 hour = 162.50 km

Answer 2

Distance = 162.5 to 2dp.

Explanation:

Alex car drives 65km = 40mins we round up to 1hr

= 1/2 x 65 + 65 = 32.5 +65 = 97.5 km p/h

Roy is 1/4 faster (As Alex speed is 3/4 of Roy)

To find 3/4 we divide by 3 then, add the 97.5 km etc..

97.5/3 = + 32.5km = 130 km/ph

To check we only have to divide by 4

130 / 4 = 32.5

We know 32.5 is 1/4 we can add this on as 15minutes.

130 km = 1hr +

32.5 km = 15 mins

Distance = 162.5 km