Question

A water park had dolphins and penguins in the ratio of 2:5. The park had 35 penguins. If the number of penguins has become double and the number of dolphins has become half, then find the present ratio of the dolphins to penguins.

• A. 2:5
• B. 4:9
• C. 6:8
• D. 1:10

Answer 1

The correct option is D 1:10

Ratio of dolphins to penguins = 2 : 5
Number of penguins in the zoo = 35

$\Rightarrow$ 2 : 5 = (no. of dolphins) : 35
(both are equivalent ratios)

$\Rightarrow$ 2 : 5 = (no. of dolphins) : 5$\times$7

$\Rightarrow$ Number of dolphins = 2 $\times$ 7 = 14

$\Rightarrow$ Number of dolphins = 14

Now, the number of penguins has become double and the number of dolphins has become half.

$\therefore$ Number of penguins = $35\times 2$ = 70
$\therefore$ Number of dolphins = $\frac{14}{2}$ = 7
Hence, the present ratio of dolphins to penguins = 7 : 70 = 1 : 10