Question

Ratios are in proportion.

• A. 2:3 and 4:5
• B. 4:5 and 12:15
• C. 3:1 and 9:1
• D. 3:4 and 6:4

Answer 1

The correct option is B 4:5 and 12:15

Two ratios are said to be in proportion if they are equivalent or equal.
Here, $\frac{4}{5}=\frac{4\times 3}{5\times 3}=\frac{12}{15}$

Hence, 4 : 5 :: 12 : 15 are in proportion.

Also product of $1^{st}$ and $4^{th}$ term should be equal to product of $2^{nd}$ and $3^{rd}$ term, which is only satisfied by 4 : 5 and 12 : 15, i.e.,
$4\times 15=5\times 12=60$.

For rest of them the product of $1^{st}$ and $4^{th}$ term is not equal to the product of $2^{nd}$ and $3^{rd}$ term.
ie. $3\times 1\ne 9\times 1$
$3\times 4\ne 4\times 6$
$2\times 5\ne 3\times 4$