Question

28 is divided into 4 parts which are in A.P. the ratio of the product of the first and third to the product of the second and fourth is 8:15 the largest part is:

• A. 6
• B. 8
• C. 10
• D. 12

Answer 1

The correct option is C 10

Since the sum is 28, we take the A.P. as 7 – 3d, 7 – d, 7 + d, 7 + 3d
$\frac{(7-3d)(7+d)}{(7-d)(7+3d)}=\frac{8}{15}\Rightarrow 15[49-14d-3d^2]=8[49+14d-3d^2]\Rightarrow 3d^2+46d-49=0\Rightarrow d=1\therefore Thepartare7-3,7-1,+1,7+3or4.6,8,10$