Problem
A hippopotamus had a mass of $29.4 \mathrm{~kg}$ at birth. At two months old, it had a mass of $78.9 \mathrm{~kg}$. By what percentage did its mass increase over these two months? Give your answer to the nearest $1 \%$.
Solution
Step 1 ：Find the difference in mass: \(78.9 - 29.4 = 49.5\)
Step 2 ：Calculate the percentage increase: \(\frac{49.5}{29.4} \times 100 = 168.37\)
Step 3 ：\boxed{168\%}
