Tina inherits $60,000 and invests it in an account earning interest at a rate of 0.5% per month - HSC - SSCE Mathematics Advanced - Question 26 - 2020 - Paper 1
Question 26
Tina inherits $60,000 and invests it in an account earning interest at a rate of 0.5% per month. Each month, immediately after the interest has been paid, Tina withd... show full transcript
Worked Solution & Example Answer:Tina inherits $60,000 and invests it in an account earning interest at a rate of 0.5% per month - HSC - SSCE Mathematics Advanced - Question 26 - 2020 - Paper 1
Step 1
a) Use the recurrence relation to find the amount of money in the account immediately after the third withdrawal.
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Answer
To find the amount in the account after three withdrawals, we will apply the recurrence relation step by step:
Thus, the amount of money in the account immediately after the third withdrawal is $58,492.49.
Step 2
b) Calculate the amount of interest earned in the first three months.
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Answer
To calculate the total interest earned in the first three months:
Total withdrawals after 3 months:
800imes3=2400
Initial balance was $60,000, and the balance after three withdrawals is:
60,000−58,492.49=1,507.51
Thus, the interest earned is:
2400−1,507.51=892.49
So, the interest earned in the first three months is $892.49.
Step 3
c) Calculate the amount of money in the account immediately after the 94th withdrawal.
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Answer
To find the amount in the account after 94 withdrawals, we can derive a formula:
The recurrence relation can be expressed as: A_n = 60,000(1.005)^n - 800 imes rac{(1.005^n - 1)}{0.005}
This formula accounts for the interest accumulated and the total withdrawals.
For n=94: A_{94} = 60,000(1.005)^{94} - 800 imes rac{(1.005^{94} - 1)}{0.005}
Calculating this yields approximately: A94extisabout187.85.
Thus, the amount of money in the account immediately after the 94th withdrawal is approximately $187.85.