Question

If a varies directly as b and if $a=4$ when $b=5$, calculate the value of a when $b=10$.

• A. $4$
• B. $5$
• C. $6$
• D. $8$
• E. $9$

Answer 1

Answer: (D)

$8$

Given,

a varies directly as $b$

when $a=4$ , $b=5$, we have to find the value of a when $b=10$

so, When $b$ is $5$, $a$ is $4$

when $b$ is $1$, $a$ = $\frac{4}{5}$ by unitary mehtod

when $b$ is $10$, $a$ = $\frac{4}{5}\times 10=8$

thus value of $a$ will be $8$