Question

The average weight of $3$ men A, B, and C in a group is $84$kg. Another man D joins the group and the average weight now becomes $80$kg. Another man E, whose weight is $3$ kg more than that of D, replaces A and the average weight of the group (B, C, D and E) becomes $79$ kg. The weight of A is

• A. $70$ kg
• B. $72$ kg
• C. $75$ kg
• D. $80$ kg

Answer 1

The correct option is C $75$ kg

$A+B+C=84\times 3=252.......\left(1\right)A+B+C+D=80\times 4=320..........\left(2\right)OnSolving\left(1\right)\&\left(2\right)D=320-252D=68E^{\prime }swt=68+3=71\therefore B+C+D+E=79\times 4\therefore B+C+D+71=316\therefore B+C+D=316-71=245Fromequation\left(2\right)\therefore (A+B+C+D)-(B+C+D)=320-245\therefore A=75Kg$