Let a ,x, y ,z b be in AP where x+y+z=15 Let a ,p,q ,r ,b be in HP where `p^(-1) +q^(-1)+r^(-1)=5/3` What is the value of ab What is the value of xyz What is the value of pqr

Options

A. 10
B. 9
C. 8
D. 6

Answer

B

Explanation

`S_(n)=(n)/(2)(a+l)`
`impliesa+x+y+z+b=(5)/(2)(a+b)`
`a+b+15=(5)/(2)(a+b)`
`implies" "a+b=10" "...(1)`
&`(1)/(a)+(1)/(p)+(1)/(q)+(1)/(r)+(1)/(b)=(5)/(2)((1)/(a)+(1)/(b))`
`implies(1)/(a)+(1)/(b)+(5)/(3)=(5)/(2)((1)/(a)+(1)/(b))`
`implies(3(a+b))/(ab)=(10)/(3)." "...(2)`
`implies(3xx10)/(ab)=(10)/(3).`
`impliesab=9`