Question 64

The average height of 30 boys out of a class of 50 is 160 cm. If the average height of the remaining boys is 165 cm, the average height of the whole class (in cm) is:

Solution

Total boys in class = 50

Average height of first 30 boys = 160 cm

=> Total height of 30 boys = $$30 \times 160=4800$$ cm

Similarly, total height of remaining 20 boys = $$20 \times 165=3300$$ cm

$$\therefore$$ Average height of the whole class = $$\frac{(4800+3300)}{30+20}$$

= $$\frac{8100}{50}=162$$ cm

=> Ans - (B)

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