The graph shows the mass, in kilograms, of Jeff's pet Atlantic cod, given its age in years. What is the age of the cod when its mass is $15 \mathrm{~kg}$ ?

![](https://cdn.mathpix.com/cropped/2024_04_20_ac36362783317e0251fdg-062.jpg?height=384&width=897&top_left_y=800&top_left_x=576)
(A) 3
(B) 7
(C) 4
(D) 6
(E) 5
A mass of $15 \mathrm{~kg}$ is halfway between $10 \mathrm{~kg}$ and $20 \mathrm{~kg}$ on the vertical axis.

The point where the graph reaches $15 \mathrm{~kg}$ is halfway between 6 and 8 on the horizontal axis.

Mass of Jeff's Pet Atlantic Cod

![](https://cdn.mathpix.com/cropped/2024_04_20_33a8a6559d675f59baa2g-122.jpg?height=323&width=892&top_left_y=473&top_left_x=671)

Therefore, the cod is 7 years old when its mass is $15 \mathrm{~kg}$.

ANSWER: (B)