If m is proportional to n and m = 5 when n = 4, then what is the value of m when n = 18?

22.5

The correct answer is Option (4) → 22.5

Since $m$ is proportional to $n$, we can express the relationship as:

$m = k \times n$

where $k$ is the constant of proportionality.

Step 1: Find the constant $k$

Using the given values $m = 5$ and $n = 4$:

$5 = k \times 4$

$k = \frac{5}{4} = 1.25$

Step 2: Calculate $m$ when $n = 18$

Now substitute the value of $k$ and the new value of $n$ into the formula:

$m = 1.25 \times 18$

$m = 22.5$

Alternatively, using the ratio method:

$\frac{m_1}{n_1} = \frac{m_2}{n_2}$

$\frac{5}{4} = \frac{m}{18}$

$m = \frac{5 \times 18}{4}$

$m = \frac{90}{4} = 22.5$

The value of $m$ when $n = 18$ is 22.5.