Here are the step-by-step solutions for the problems on the worksheet.
1. $300 at 7.5% for 5 years
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Formula: Interest = Principal × Rate × Time
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Step 1: Convert the percentage to a decimal: $7.5\% = 0.075$.
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Step 2: Multiply the numbers: $300 \times 0.075 \times 5$.
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Calculation: $300 \times 0.075 = 22.5$. Then, $22.5 \times 5 = 112.5$.
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Answer: $112.50
2. $770 at 16% for 6 months
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Step 1: Convert time to years. Since there are 12 months in a year, 6 months is $\frac{6}{12}$ or $0.5$ years.
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Step 2: Convert rate to decimal: $16\% = 0.16$.
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Step 3: Calculate: $770 \times 0.16 \times 0.5$.
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Calculation: $770 \times 0.16 = 123.2$. Then, $123.2 \times 0.5 = 61.6$.
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Answer: $61.60
3. $668 at 9.25% for 15 months
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Step 1: Convert time to years: $\frac{15}{12} = 1.25$ years.
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Step 2: Convert rate to decimal: $9.25\% = 0.0925$.
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Step 3: Calculate: $668 \times 0.0925 \times 1.25$.
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Calculation: $668 \times 0.0925 = 61.79$. Then, $61.79 \times 1.25 = 77.2375$.
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Rounding: Round to the nearest cent (two decimal places). Since the third decimal is 7, round up.
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Answer: $77.24
4. $285 at 8.5% for 2 ½ years
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Step 1: Convert time to a decimal: $2 \frac{1}{2} = 2.5$ years.
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Step 2: Convert rate to decimal: $8.5\% = 0.085$.
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Step 3: Calculate: $285 \times 0.085 \times 2.5$.
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Calculation: $285 \times 0.085 = 24.225$. Then, $24.225 \times 2.5 = 60.5625$.
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Rounding: Round to the nearest cent. Since the third decimal is 2, keep it as is.
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Answer: $60.56
5. $360 at 185% for 2 years
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Step 1: Convert rate to decimal: $185\% = 1.85$.
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Step 2: Calculate: $360 \times 1.85 \times 2$.
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Calculation: $360 \times 1.85 = 666$. Then, $666 \times 2 = 1332$.
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Answer: $1,332.00
6. $175 at 5.45% for 30 months
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Step 1: Convert time to years: $\frac{30}{12} = 2.5$ years.
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Step 2: Convert rate to decimal: $5.45\% = 0.0545$.
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Step 3: Calculate: $175 \times 0.0545 \times 2.5$.
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Calculation: $175 \times 0.0545 = 9.5375$. Then, $9.5375 \times 2.5 = 23.84375$.
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Rounding: Round to the nearest cent. Since the third decimal is 3, keep it as is.
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Answer: $23.84
7. Sarah invested $150 at 8% simple interest. What is the total amount of money after 3 years?
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Step 1: Find the interest first.
* $150 \times 0.08 \times 3$
* $150 \times 0.08 = 12$
* $12 \times 3 = 36$ (Interest is $36)
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Step 2: Add the interest to the original investment (Principal) to get the Total Amount.
* $150 + 36 = 186$
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Answer: $186.00
8. Ben borrowed $800 at 9% simple interest for 2 years. What is the total amount he must repay?
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Step 1: Find the interest first.
* $800 \times 0.09 \times 2$
* $800 \times 0.09 = 72$
* $72 \times 2 = 144$ (Interest is $144)
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Step 2: Add the interest to the borrowed amount (Principal) to get the Total Repayment.
* $800 + 144 = 944$
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Answer: $944.00
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Final Answer:
1. $112.50
2. $61.60
3. $77.24
4. $60.56
5. $1,332.00
6. $23.84
7. $186.00
8. $944.00
Parent Tip: Review the logic above to help your child master the concept of simple compound interest worksheet.
