Question

Walter takes 7/10 of an hour to mow 2/5 of an acre of lawn. At this rate, how many acres will he mow in an hour?

A. 7/25 ares

B. 4/7 ares

C.1 1/5 ares

D.1 3/4 ares

Answer 1

To determine how many acres Walter can mow in one hour, we first find his rate of mowing.

1. Walter takes \( \frac{7}{10} \) of an hour to mow \( \frac{2}{5} \) of an acre. To find his rate in acres per hour, we calculate:
\[
\text{Rate} = \frac{\text{Acres}}{\text{Time}} = \frac{\frac{2}{5} \text{ acres}}{\frac{7}{10} \text{ hours}}
\]

2. Dividing by a fraction is equivalent to multiplying by its reciprocal, so we have:
\[
\text{Rate} = \frac{2}{5} \times \frac{10}{7}
\]

3. Now, we multiply the fractions:
\[
\text{Rate} = \frac{2 \times 10}{5 \times 7} = \frac{20}{35}
\]

4. Simplifying \( \frac{20}{35} \):
\[
\frac{20}{35} = \frac{4}{7} \text{ acres per hour}
\]

Thus, the rate at which Walter mows is \( \frac{4}{7} \) acres per hour.

The answer is:

**B. \( \frac{4}{7} \) acres**