Question: top-center: A hippopotamus had a mass of $31.2$ kg at birth.
top-center: At two months old, it had a mass of $84.7$ kg.
center: By what percentage did its mass increase over these two months?
bottom-center: Give your answer to the nearest 1%
1. **State the problem:** We want to find the percentage increase in the hippopotamus's mass from birth to two months old.
2. **Formula for percentage increase:**
$$\text{Percentage Increase} = \left(\frac{\text{New Mass} - \text{Original Mass}}{\text{Original Mass}}\right) \times 100\%$$
3. **Identify values:**
- Original Mass = $31.2$ kg
- New Mass = $84.7$ kg
4. **Calculate the increase in mass:**
$$84.7 - 31.2 = 53.5 \text{ kg}$$
5. **Calculate the percentage increase:**
$$\frac{53.5}{31.2} \times 100\%$$
6. **Simplify the fraction:**
$$\frac{53.5}{31.2} = \frac{\cancel{53.5}}{\cancel{31.2}} \approx 1.715\quad \text{(approximate)}$$
7. **Multiply by 100 to get percentage:**
$$1.715 \times 100\% = 171.5\%$$
8. **Round to the nearest 1%:**
$$172\%$$
**Final answer:** The hippopotamus's mass increased by approximately $172\%$ over the two months.