# CAT Practice : Averages, Ratios, Mixtures

Averages

## Averages

Q.39: A group of 20 people has the oldest person with 90 years of age. The average of the group is reduced by 4, if the oldest person is reduced by someone new, Find the age of the new person.
1. 80 years
2. 60 years
3. 30 years
4. 10 years

Choice D. 10 years

## Detailed Solution

Let the distance travelled be d.

Average Speed = Total Distance Travelled/Total time taken

=$\frac{d}{\frac{d}{2*80}} + \frac{d}{4*40} + \frac{d}{4*20} = \frac{1}{\frac{(1+1+2)}{160}} = \frac{160}{4} = 40 Kmph$

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