Question

1. a woman put $580 into an account for one year. she earned $35 in interest. what is the percentage of interest?
2. a student answered 86 problems out of 120 on a test correctly. what percentage did she get on the test? (round to the nearest whole number)
3. manuel bought a wrecked dodge challenger that he could fix. he bought it for $360 less than the original price of $7200. how much of a discount did he get?
4. pamela bought an electric drill at 85% of the regular price. the regular price was $59 for the drill. how much did she pay?
5. a crew is made up of 8 men and 16 women. what percent of the crew are women?
6. ben earns $12,800 a year. about 15% is taken out for taxes. how much is taken out for taxes?
7. at a sale, shirts were originally $15 each. the sale price was 20% off of their original price. how much was the discount?
8. a student earned a grade of 80% on a math test that had 20 problems. how many problems on this test did the student answer correctly? (round to the nearest whole number)
9. a metal bar weighs 8.15 ounces. 93% of the bar is silver. how many ounces of silver are in the bar? (round to the nearest thousandth)

Explanation:

Step1: Identify the problem - percentage calculation

We will solve each problem one - by - one using percentage formulas.

Problem 4

The interest amount is $35$ and the principal is $580$. The formula for percentage of interest is $\text{Percentage}=\frac{\text{Interest}}{\text{Principal}}\times100$.
$\frac{35}{580}\times100\approx6.03\%$ (already given in the table).

Problem 5

The number of correct answers is $86$ and the total number of questions is $120$. The percentage is $\frac{86}{120}\times100\approx71.67\%$, rounded to the nearest whole number is $72\%$.

Problem 6

The discount amount is $360$ and the original price is $7200$. The discount percentage is $\frac{360}{7200}\times100 = 5\%$ (the value in the table $4.76\%$ seems to be incorrect as $\frac{360}{7560}\approx4.76\%$, but the original price should be $7200$ according to the problem).

Problem 7

The drill is bought at $85\%$ of the regular price. If the regular price is $59$, then the price paid is $0.85\times59 = 50.15$.

Problem 8

The number of women is $16$ and the total number of crew members is $8 + 16=24$. The percentage of women is $\frac{16}{24}\times100\approx66.67\%$.

Problem 9

Ben's annual income is $12800$ and the tax rate is $15\%$. The amount taken out for taxes is $0.15\times12800 = 1920$.

Problem 10

The original price of a shirt is $15$ and the discount rate is $20\%$. The discount amount is $0.20\times15 = 3$.

Problem 11

The student got $80\%$ on a test with $20$ problems. The number of correct problems is $0.80\times20 = 16$.

Problem 12

The weight of the metal bar is $8.15$ ounces and $93\%$ of it is silver. The amount of silver is $0.93\times8.15 = 7.5795\approx7.580$ ounces.

Answer:

Problem 4: $6.03\%$

Problem 5: $72\%$

Problem 6: $5\%$

Problem 7: $50.15$

Problem 8: $66.67\%$

Problem 9: $1920$

Problem 10: $3$

Problem 11: $16$

Problem 12: $7.580$ ounces