The time period of planet X around sun is 8 times that of Y. The distance of X from the sun is how many times greater than that of Y ?

Options

A. 4 times
B. 3 times
C. `6(1)/(2)` times
D. `5(1)/(2)` times

Answer

A

Explanation

`(T_(1)^(2))/(T_(2)^(2)) = ((R_(1))/(R_(2)))^(3) rArr (R_(1))/(R_(2)) = ((T_(1))/(T_(2)))^(2//3)`
`(R_(1))/(R_(2))=(8)^(2//3) rArr R_(1)=4R_(2)`.
Thus correct choice is (a).