Question

Of the labeled points, which represents the animal for which the ratio of life expectancy to gestation period is greatest?

• A. A
• B. B
• C. C
• D. D

Answer 1

Answer: (A)

A

As seen in the graph alongside, we have life expectancy on the y axis and gestation period on the $x$ axis.

For point A, the ratio of life expectancy to gestation period is $\frac{7}{22.5}=\frac{14}{45}$

For point B, the ratio is $\frac{8}{45}$

It is visible that the $y$ coordinate is greater at $Y$ than $X$, which have the same $x$ coordinate and so we only look at the ratio at $D$, which is $\frac{10}{51}$.

Since $\frac{14}{45}>\frac{8}{45}$, we only need to compare $\frac{14}{45}$ and $\frac{10}{51}$.

$14\times 51=714$ and $45\times 10=450$

$\Rightarrow \frac{14}{45}>\frac{10}{51}$

Hence, the ratio of life expectancy to gestation period is greatest at point A.