Average weight of 3 ,cm men A , B , C is 84 ,kg . Another man D joins group and average now becomes

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Average weight of $3 \,cm$ men $A , B , C$ is $84 \,kg$. Another man $D$ joins the group and the average now becomes $80 \,kg$. If another man $E$ whose weight is $3 \,kg$ more than that of $D$ replaces $A$ then the averageweight of $B , C , D$ and $E$ becomes $79\, kg .$ The weight of $A$ in $kg$ is

A

$80$

B

$72$

C

$70$

D

$75$

Solution

$A+B+C=3 \times 84=252$

$A+B+C+D=80 \times 4=320$

$D$'s age $=320-252=68 kg$

Then $E$ 's age $=68+3=71 kg$

Now $B + C + D + E =79 \times 4=316$

$B+C+68+71=316$

$B+C=177$

Put value of $B + C$ is (1)

$A=252-177=75 \,kg$

Standard 13

Quantitative Aptitude

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