Question

The ratio of $9$ days to $3$ weeks is:

• A. $3:1$
• B. $9:3$
• C. $3:7$
• D. $1:3$

Answer 1

The correct option is C

$3:7$

Explanation for the correct option:

We can write $9$ days to $3$ weeks Here units are not same.

Convert it into same units. $3week=3\times 7days=21days$

Express it as $9daysto21days$ i.e. $\frac{9}{21}$

Find the HCF of numerator $9$ and denominator $21$.

By the method of prime factorisation,

$9=3^2$

$21=3\times 7$

$HCF(9,21)=3$

Divide both the numerator and denominator by HCF

$=$$\frac{9÷3}{21÷3}$

$=$$\frac{3}{7}$

Therefore, $9$ days to $3$ weeks can be expressed in simplest form as $3:7$.

Hence, option(C) is correct.