Question
Question 3 Calculate the accumulated amount after eight years of weekly payments of R1 900 each into an account earning \( 9,7 \% \) interest per year, compounded weekly. Draw an appropriate timeline showing all the given values. Question 4 Nolwazi wants to buy a new state of the art computer for R35 000. She decides to save by depositing an amount of R500 every month into an account carning \( 11,32 \% \) interest per year, compounded monthly. How many years (accurate to one decimal place) will it take Nolwazi to have R35 000 available?
Ask by Medina Schultz.
Feb 16,2025 04:07
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Answer
**Question 3:**
After 8 years of depositing R1,900 each week into an account earning 9.7% annual interest compounded weekly, the total accumulated amount will be approximately R1,192,000.
**Question 4:**
Nolwazi will need to save for approximately 4.5 years to reach R35,000 by depositing R500 monthly into an account with 11.32% annual interest compounded monthly.
Solution
Below are the step‐by‐step solutions for both questions.
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Question 3
We are given:
• Payment amount, P = R1 900 per week
• Annual interest rate = 9.7% compounded weekly
• Total time = 8 years
Step 1. Determine the number of compounding periods:
Since interest is compounded weekly and there are 52 weeks in a year,
n = 8 × 52 = 416 weeks.
Step 2. Calculate the periodic (weekly) interest rate:
i = 9.7%/52 = 0.097/52 ≈ 0.0018654 per week
Step 3. Future value of an ordinary annuity:
Payments are made at the end of each period. The future value is given by
A = P × [((1 + i)ⁿ – 1) / i]
Substitute the values:
A = 1900 × [((1 + 0.0018654)^(416) – 1) / 0.0018654]
Let’s approximate (1 + 0.0018654)^(416). One way is to use logarithms:
ln(1.0018654) ≈ 0.001863, so
ln((1.0018654)^(416)) ≈ 416 × 0.001863 ≈ 0.775,
which gives
(1.0018654)^(416) ≈ e^(0.775) ≈ 2.17.
Thus,
A ≈ 1900 × [(2.17 – 1) / 0.0018654]
= 1900 × (1.17 / 0.0018654)
≈ 1900 × 627.9
≈ R1,192,000
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Timeline for Question 3
Time (in weeks) Action
Week 0 Start (initial balance = 0)
Week 1 Deposit R1 900 (end of first week)
Week 2 Deposit R1 900
⋮
Week 415 Deposit R1 900
Week 416 Deposit R1 900 (last deposit)
After week 416 Account has accumulated interest on all deposits to ≈ R1,192,000
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Question 4
We are given:
• Nolwazi must have R35 000 to buy the computer.
• She deposits R500 every month.
• Interest rate = 11.32% per year compounded monthly.
Step 1. Determine the periodic (monthly) interest rate:
i = 11.32%/12 = 0.1132/12 ≈ 0.0094333 per month
Step 2. Let n be the number of monthly deposits needed. The future value of an ordinary annuity is given by
A = P × [((1 + i)ⁿ – 1) / i]
We set A = 35,000 and P = 500:
35,000 = 500 × [((1.0094333)ⁿ – 1) / 0.0094333]
Solve for ((1.0094333)ⁿ – 1):
((1.0094333)ⁿ – 1) = 35,000 × 0.0094333 / 500
Calculate the right‐side:
35,000/500 = 70, so
((1.0094333)ⁿ – 1) = 70 × 0.0094333 ≈ 0.66
Thus,
(1.0094333)ⁿ ≈ 1 + 0.66 = 1.66
Step 3. Solve for n using logarithms:
n = ln(1.66) / ln(1.0094333)
Calculate:
ln(1.66) ≈ 0.507 and ln(1.0094333) ≈ 0.00939,
n ≈ 0.507 / 0.00939 ≈ 54
Since n = 54 months, the number of years is:
54/12 = 4.5 years
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Final Answers
Question 3: After 8 years (416 weeks) of depositing R1 900 each week into an account earning 9.7% per annum compounded weekly, the accumulated amount will be approximately R1,192,000.
Question 4: Nolwazi needs to save for about 54 months, which is approximately 4.5 years, to have R35 000 in her account when depositing R500 every month at 11.32% per annum compounded monthly.
Answered by UpStudy AI and reviewed by a Professional Tutor
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Simplify this solution Mind Expander
The formula for calculating the future value of a series of regular payments (also known as an annuity) can be quite useful here! For the first question, you’ll want to use the future value of an annuity formula:
\[ FV = P \times \frac{(1 + r/n)^{nt} - 1}{(r/n)} \]
where \( P \) is the payment per period (R1,900), \( r \) is the annual interest rate (0.097), \( n \) is the number of compounding periods per year (52), and \( t \) is the number of years (8). Plug in those values, and you’ll get the accumulated amount after eight years!
As for Nolwazi's savings goal, similar principles apply! To find out how long it would take her to reach R35,000 by depositing R500 monthly into an account with 11.32% interest, you can use the formula for the future value of a series of cash flows. Rearranging the formula to solve for \( t \) might feel tricky, but with some manipulation and a financial calculator, you’ll get the number of years she'll need to save! It’s all about patience and perseverance!
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