Question:medium

Mira and Amal walk along a circular track, starting from the same point at the same time. If they walk in the same direction, then in 45 minutes, Amal completes exactly 3 more rounds than Mira. If they walk in opposite directions, then they meet for the first time exactly after 3 minutes. The number of rounds Mira walks in one hour is

Updated On: Jan 15, 2026
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Solution and Explanation

Let \( a \) represent the time in minutes for Amal to finish one round and \( m \) represent the time in minutes for Mira to finish one round.

In 45 minutes:
Amal's rounds completed = \( \dfrac{45}{a} \)
Mira's rounds completed = \( \dfrac{45}{m} \)

Amal completed 3 more rounds than Mira in 45 minutes:
\[ \dfrac{45}{a} = \dfrac{45}{m} + 3 \] This simplifies to:
\[ \dfrac{1}{a} - \dfrac{1}{m} = \dfrac{1}{15} \tag{1} \]

Together, they complete 1 round in 3 minutes:
\[ \dfrac{3}{a} + \dfrac{3}{m} = 1 \Rightarrow \dfrac{1}{a} + \dfrac{1}{m} = \dfrac{1}{3} \tag{2} \]

Solving equations (1) and (2) simultaneously:
Subtracting (1) from (2): \[ \left( \dfrac{1}{a} + \dfrac{1}{m} \right) - \left( \dfrac{1}{a} - \dfrac{1}{m} \right) = \dfrac{1}{3} - \dfrac{1}{15} \Rightarrow \dfrac{2}{m} = \dfrac{4}{15} \Rightarrow \dfrac{1}{m} = \dfrac{2}{15} \Rightarrow m = \dfrac{15}{2} = 7.5 \]

Therefore, Mira requires 7.5 minutes to complete one round.
In 1 hour (60 minutes), Mira completes:
\[ \text{Number of rounds} = \dfrac{60}{7.5} = 8 \]

Mira completes 8 rounds in 1 hour.

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