CEMC Fermat, 2023

Algebra Difficulty 1.3 Junior Find the answer Canada

A bicycle trip is 30 km long. Ari rides at an average speed of 20
km/h. Bri rides at an average speed of 15 km/h. If Ari and Bri begin at
the same time, how many minutes after Ari finishes the trip will Bri
finish?

Pick one

Solution

Riding at 15 km/h, Bri finishes the 30 km in $\dfrac{30\text{ km}}{15\text{ km/h}} = 2\text{ h}$ .

Riding at 20 km/h, Ari finishes the 30 km in $\dfrac{30\text{ km}}{20\text{ km/h}} = 1.5\text{ h}$ .

Therefore, Bri finishes 0.5 h after Ari, which is 30 minutes.

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