The average weight of 30 boys and girls is 45 kg . If the average weight of 20 boys out of them 43.5 kg , then average weight of 10 girls is : A ) 58 kg C ) 52 kg ( B ) 48 kg ( D ) 50 kg .
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The correct answer is (B) 48 kg
Let mass of total students is x
Then
X / 30 = 45 I.e. X = 1350 kg
Let mass of boys is A
Then
A / 20 = 43.5 I.e. A = 870 kg
So
Mass of girls = X - A
= 1350 - 870
= 480 kg
Average mass = 480 / 10
= 48 kg
Let mass of total students is x
Then
X / 30 = 45 I.e. X = 1350 kg
Let mass of boys is A
Then
A / 20 = 43.5 I.e. A = 870 kg
So
Mass of girls = X - A
= 1350 - 870
= 480 kg
Average mass = 480 / 10
= 48 kg
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