Maths Olympiad Prep

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, 2020

Algebra Difficulty 1.4 Junior Find the answer Canada

Emil and Olivia ran a race. Their race times totalled 1 hour 52 minutes. If Emil’s time was 4 minutes less than Olivia’s time, how many minutes did it take Olivia to run the race?

Pick one

Solutions — 2

Solution 1

Solution 1

There are 60 minutes in 1 hour, and so there are 60+52=11260+52=112 minutes in 1 hour 52 minutes.

If Emil’s race time was 54 minutes, then Olivia’s race time was 4 minutes more, or 58 minutes.

In this case, their race times total 54+58=11254+58=112 minutes, as required.
Therefore, it took Olivia 58 minutes to run the race.

Solution 2

As in Solution 1, the total of their race times is 112 minutes.

If Emil’s race time was 4 minutes more, then his race time would be equal to Olivia’s, and the total of their race times would be 112+4=116112+4=116 minutes.

If their race times are equal and total 116 minutes, then they each finished the race in 116÷2=58116\div2=58 minutes.
Therefore, it took Olivia 58 minutes to run the race.

Solution 2

The yy-coordinates of points P(15,55)P(15,55) and Q(26,55)Q(26,55) are equal.

Therefore, the distance between PP and QQ is equal to the positive difference between their xx-coordinates, or 2615=1126-15=11.

Similarly, the xx-coordinates of points R(26,35)R(26,35) and Q(26,55)Q(26,55) are equal.

Therefore, the distance between RR and QQ is equal to the positive difference between their yy-coordinates, or 5535=2055-35=20.
Since PQ=11PQ=11 and RQ=20RQ=20, the area of rectangle PQRSPQRS is 11×20=22011\times20=220.

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Source: CEMC, University of Waterloo, licensed CC-BY-NC-4.0. Statement reproduced verbatim; metadata (topic, difficulty) added by this project.