Percent Problems: Practice

The rate is $25\% = 0.25$ and the whole is $80$, so multiply.

$p = 0.25 \times 80 = 20$

Since $25\%$ is a quarter, this is $80 \div 4 = 20$.

Convert to the decimal rate $40\% = 0.40$ and multiply by $150$.

$p = 0.40 \times 150 = 60$

The part is $15$ and the whole is $60$, so the rate is $r = \frac{p}{w}$.

$r = \frac{15}{60} = 0.25 = 25\%$

Divide the part by the whole to get the rate, then write it as a percent.

$r = \frac{18}{90} = 0.20 = 20\%$

The part is $12$ and the rate is $25\% = 0.25$, and the whole is unknown. Solve $r\,w = p$ by dividing.

$w = \frac{12}{0.25} = 48$

Divide the part by the rate to recover the whole.

$w = \frac{20}{0.40} = 50$

A percent means divide by $100$, which moves the point two places left.

$45\% = \frac{45}{100} = 0.45$

Divide the part by the whole to find the rate.

$r = \frac{36}{40} = 0.90 = 90\%$

The rate is $75\% = 0.75$, so multiply by $40$.

$p = 0.75 \times 40 = 30$

Since $75\%$ is three quarters, this is $3 \times (40 \div 4) = 3 \times 10 = 30$.

Divide the part by the rate to recover the whole.

$w = \frac{24}{0.30} = 80$

The rate is $5\% = 0.05$, so multiply by $200$.

$p = 0.05 \times 200 = 10$

Divide the part by the whole and write the decimal as a percent.

$r = \frac{63}{90} = 0.70 = 70\%$