Money And Consumer Math Worksheets pdf | Math Champions - Free Printable

Let's solve each of these simple interest problems step by step. The formula for simple interest is:

$$
I = P \times r \times t
$$

Where:
- $ I $ = Interest earned or paid
- $ P $ = Principal (initial amount)
- $ r $ = Annual interest rate (as a decimal)
- $ t $ = Time in years

The final balance is:
$$
A = P + I = P(1 + rt)
$$

---

Problem 1

> If you borrow $974 for eight years at an interest rate of 9%, how much interest will you pay?

- $ P = 974 $
- $ r = 0.09 $
- $ t = 8 $

$$
I = 974 \times 0.09 \times 8 = 974 \times 0.72 = 700.32
$$

✔ Answer: $700.32

---

Problem 2

> If an investment over seven years at a rate of $374.64 results in a final balance of $1,266.64, what was the original investment?

Wait — this wording is ambiguous. It says “at a rate of $374.64” — that can't be right. Interest rates are percentages, not dollar amounts.

But let’s assume it means:
> The interest earned is $374.64 over 7 years, and the final balance is $1,266.64.

Then:
- $ I = 374.64 $
- $ t = 7 $
- $ A = 1266.64 $

We know:
$$
A = P + I \Rightarrow P = A - I = 1266.64 - 374.64 = 892
$$

✔ Answer: $892

Alternatively, if the problem meant that the interest rate is 374.64%, that would be extremely high and unrealistic. So the most logical interpretation is that $374.64 is the interest earned.

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Problem 3

> If a principal of $244 was invested at a rate of 9% and terminates with a balance of $441.64, how long was the money invested for?

- $ P = 244 $
- $ r = 0.09 $
- $ A = 441.64 $
- Find $ t $

First, find interest:
$$
I = A - P = 441.64 - 244 = 197.64
$$

Now use:
$$
I = P \cdot r \cdot t \Rightarrow 197.64 = 244 \times 0.09 \times t
$$
$$
197.64 = 21.96t \Rightarrow t = \frac{197.64}{21.96} = 9
$$

✔ Answer: 9 years

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Problem 4

> You put $224 into an investment at 10% for five years. What will the balance be at the end of five years?

- $ P = 224 $
- $ r = 0.10 $
- $ t = 5 $

$$
I = 224 \times 0.10 \times 5 = 224 \times 0.5 = 112
$$
$$
A = 224 + 112 = 336
$$

✔ Answer: $336

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Problem 5

> You take out a loan for $818 at an interest rate of 10% for five years. What is the total amount that you will have at the end of the five years?

This is the same as Problem 4 but for a loan.

- $ P = 818 $
- $ r = 0.10 $
- $ t = 5 $

$$
I = 818 \times 0.10 \times 5 = 818 \times 0.5 = 409
$$
$$
A = 818 + 409 = 1227
$$

✔ Answer: $1,227

---

Problem 6

> If you received $58.40 on $730 invested at a rate of 4%, for how long did you invest the principal?

- $ I = 58.40 $
- $ P = 730 $
- $ r = 0.04 $
- Find $ t $

$$
I = P \cdot r \cdot t \Rightarrow 58.40 = 730 \times 0.04 \times t = 29.2t
\Rightarrow t = \frac{58.40}{29.2} = 2
$$

✔ Answer: 2 years

---

Problem 7

> If a principal of $121 was invested at a rate of 6% and terminates with a balance of $171.82, how long was the money invested for?

- $ P = 121 $
- $ r = 0.06 $
- $ A = 171.82 $

$$
I = 171.82 - 121 = 50.82
$$
$$
I = P \cdot r \cdot t \Rightarrow 50.82 = 121 \times 0.06 \times t = 7.26t
\Rightarrow t = \frac{50.82}{7.26} = 7
$$

✔ Answer: 7 years

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Problem 8

> How long must $661 be invested at a rate of 7% to earn $46.27 in interest?

- $ P = 661 $
- $ r = 0.07 $
- $ I = 46.27 $

$$
I = P \cdot r \cdot t \Rightarrow 46.27 = 661 \times 0.07 \times t = 46.27t
\Rightarrow t = \frac{46.27}{46.27} = 1
$$

✔ Answer: 1 year

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Problem 9

> The cost of a loan for $406 over seven years is $198.94. What was the rate on the loan?

- $ P = 406 $
- $ t = 7 $
- $ I = 198.94 $
- Find $ r $

$$
I = P \cdot r \cdot t \Rightarrow 198.94 = 406 \times r \times 7 = 2842r
\Rightarrow r = \frac{198.94}{2842} \approx 0.07
$$

Convert to percent: $ 0.07 = 7\% $

✔ Answer: 7%

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✔ Final Answers Summary:

1. $700.32
2. $892
3. 9 years
4. $336
5. $1,227
6. 2 years
7. 7 years
8. 1 year
9. 7%

Let me know if you'd like these written neatly for printing or explanation!