Question

Suppose y varies directly with x if y=27 when x=3 what is y when x=5

Answer 1

The value of y when x = 5 is 45

Solution:

Given that y varies directly with x. This can be written mathematically as:

y  ∝  x

$y = k \times x$  ---- eqn 1

Where "k" is the constant of propotionality

Given y = 27 when x = 3. Substitute these values in eqn 1

$27 = k \times 3\\\\k = \frac{27}{3} = 9$

k = 9

Substitute k = 9 in eqn 1

y = 9x ----- eqn 2

To find: y = ? and x = 5

Substitute x = 5 in eqn 2

$y = 9 \times 5 = 45$

Thus the value of y when x = 5 is 45