The average weight of 25 candles is 40 grams. If some candles of weight 50 grams each were removed, then average weight becomes 37.5 grams. How many candles of weight 50 grams each were removed?
Average weight of 25 candles = 40 grams
=> Total weight of 25 candles = $$40\times25=1000$$ grams
Let $$n$$ candles of 50 grams of weight were removed, then
=> $$\frac{1000-50n}{25-n}=37.5$$
=> $$1000-50n=937.5-37.5n$$
=> $$50n-37.5n=1000-937.5$$
=> $$12.5n=62.5$$
=> $$n=\frac{62.5}{12.5}=5$$
=> Ans - (B)
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