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[Wonder Boy]

question asked by @lalithasrip : In a class the ratio of the no. of boys to girls is 7:3 each boy is given only a 50 paise coin and each girl given 75 paise coin. the differences in the amount present with boys and girls is rs. 3.75 how many coins should the boys and girls exchange so that the amount with the boys becomes twice the amount with the girls ?
a. 8
b 6
c4
d 9

[Wonder Boy]

@lalithasrip here is the solution for ur question :
Lets suppose the no. of boys and girls be 7x and 3x .
so 7x(0.5) – 3x(0.75) = 3.75
-> 14x – 9x = 15 -> x = 3
so there are 7.3 = 21 boys and 3.3 = 9 girls.
Let y of them exchange coins
so (21-y)0.5 + 0.75 y = 2[(9-y) 0.75 +0.5 y]
-> 42 -2y + 3y = 54-6y + 4y -> 42+y =54-2y
-> 3y = 12 -> y = 4
so they exchanged 4 coins . Ans 🙂

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