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Arun, Barun and Kiranmala start from the same place and travel in the same direction at speeds of $30, 40$ and $60$ km per hour respectively. Barun starts two hours after Arun. If Barun and Kiranmala overtake Arun at the same time instant, How many hours after Arun did Kiranmala start?

1. $3$
2. $3.5$
3. $4$
4. $4.5$
5. $5$

Arun has travelled 60 km when Barun starts.

Barun overtakes Arun in $\frac{60}{40-30}$ = 6 hrs

In this time, Barun travels 6 × 40 = 240 km from the starting point.

Kiranmala overtakes Arun at the same point.

Kiranmala takes $\frac{240}{60}$ = 4 hrs to reach there.

Arun takes $\frac{240}{30}$ = 8 hrs to reach there.

Kiranmala starts 8 – 4 = 4 hrs after Arun.

Hence, option (3)4 is the Answer.

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