Commercial arithmetic: simple interest — KCSE Mathematics

KCSE Mathematics · 106 practice questions · 3 syllabus objectives

37 easy38 medium31 hard

What You'll Learn

Key learning outcomes for this topic, aligned to the KNEC KCSE syllabus.

Define simple interest and apply the formula I = PRT/100 to calculate interest, principal, rate or time

Calculate the total amount after a period using A = P + I = P(1 + RT/100); solve for any one variable given the others

Commercial arithmetic: simple interest

Sample Questions

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1
easySHORT ANSWER2 marks

A school invested Ksh 50,000 at a simple interest rate of 8% per annum. Calculate the interest earned after 3 years. (2 marks)

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Part (a) — 2 marks
I = PRT/100 = 50000 × 8 × 3 / 100 (1 mk)
I = Ksh 12,000 (1 mk)
2
easySHORT ANSWER3 marks

Define simple interest and calculate the interest earned on Ksh 15,000 at a rate of 5% per annum over 3 years. (3 marks)

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Part (a) — 1 mark
Simple interest is the interest calculated on the principal amount only. (1 mk)
Part (b) — 2 marks
I = PRT/100 = 15000 × 5 × 3 / 100 (1 mk)
I = Ksh 2250 (1 mk)
3
easySHORT ANSWER3 marks

A sum of Ksh 15,000 is invested at a simple interest rate of 5% per annum. Calculate the total amount after 3 years. (3 marks)

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Part (a) — 3 marks
Calculate interest using I = PRT/100: I = 15000 × 5 × 3 / 100 (1 mk)
Interest earned is Ksh 2,250 (1 mk)
Total amount A = P + I = 15000 + 2250 = Ksh 17,250 (1 mk)
4

Define simple interest and calculate the interest earned on a principal of Ksh 15,000 at a rate of 5% per annum over 3 years. (3 marks)

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