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Here are the interest rates for two bank accounts - OCR - GCSE Maths - Question 23 - 2018 - Paper 1

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Here are the interest rates for two bank accounts. Northern Savings Bank (NSB) 2.5% per year compound interest Central Alliance Bank (CAB) 2.7% per year simple int... show full transcript

Worked Solution & Example Answer:Here are the interest rates for two bank accounts - OCR - GCSE Maths - Question 23 - 2018 - Paper 1

Step 1

Calculate the final amount in Northern Savings Bank (NSB) after 8 years using compound interest.

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Answer

To find the total amount in the NSB account after 8 years with a compound interest rate of 2.5%, we use the formula:

A=P(1+r)tA = P(1 + r)^t

Where:

  • AA is the amount of money accumulated after n years, including interest.
  • PP is the principal amount (£6400).
  • rr is the annual interest rate (2.5% = 0.025).
  • tt is the time the money is invested for (8 years).

Thus, we calculate:

ANSB=6400(1+0.025)8A_{NSB} = 6400(1 + 0.025)^8 ANSB=6400(1.025)8A_{NSB} = 6400(1.025)^8 ANSB=6400imes1.21899ext(approx)A_{NSB} = 6400 imes 1.21899 ext{ (approx)} ANSBext(afterrounding)=£7807.18A_{NSB} ext{ (after rounding)} = £7807.18

Step 2

Calculate the final amount in Central Alliance Bank (CAB) after 8 years using simple interest.

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Answer

For the CAB account, the simple interest formula is used:

A=P(1+rt)A = P(1 + rt)

Where:

  • AA is the total amount of money.
  • PP is the principal amount (£6400).
  • rr is the annual interest rate (2.7% = 0.027).
  • tt is the time the money is invested for (8 years).

Therefore:

ACAB=6400(1+0.027imes8)A_{CAB} = 6400(1 + 0.027 imes 8) ACAB=6400(1+0.216)A_{CAB} = 6400(1 + 0.216) ACAB=6400imes1.216A_{CAB} = 6400 imes 1.216 ACABext(afterrounding)=£7785.44A_{CAB} ext{ (after rounding)} = £7785.44

Step 3

Calculate the difference in value between the two accounts after 8 years.

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Answer

Finally, to find the difference between the two final amounts:

extDifference=ANSBACAB ext{Difference} = A_{NSB} - A_{CAB} extDifference=7807.187785.44 ext{Difference} = 7807.18 - 7785.44 extDifference=£21.74 ext{Difference} = £21.74

Thus, the difference in value after 8 years is £21.74.

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