Question

What number should be divided by (0.81)1/2 to give the result as 81?
(a) 9
(b) 81
(c) 72.9
(d) 0.9 ​

Answer 1

answer : option (c) 72.9

explanation : Let unknown number is x

a/c to question,

if x is divided by $(0.81)^{1/2}$ to give the result as 81.

so, x/(0.81)½ = 81

we know, 0.81 = 0.9 × 0.9 = (0.9)²

so, (0.81)½ = (0.9²)½ = 0.9

now, x/0.9 = 81

or, x = 0.9 × 81 = 72.9

hence, option (c) 72.9 should be divided by (0.81)½ to give the result as 81.