CMA Foundation · Fundamentals of Business Mathematics and Statistics · Arithmetic Progression and Geometric Progression
The first term of a geometric progression is 5 and its fourth term is 40. What is the common ratio?
The common ratio is 2. The fourth term of a GP equals the first term times r cubed, so 5r^3 = 40, which gives r^3 = 8 and r = 2. The sequence 5, 10, 20, 40 confirms this.
- A2Correct
- B3
- C8
- D4
Explanation
The fourth term is ar^3, so 5r^3 = 40 and r^3 = 8, giving r = 2. Check: 5, 10, 20, 40. The value 8 is wrong because it is r^3, not r.
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