CA Foundation · Quantitative Aptitude · Sequence and Series
A textile firm's production capacity in successive months forms a geometric sequence. If the production in month 2 is 1,200 units and month 5 is 9,600 units, what is the production in month 1?
Production in month 1 is 600 units. Since month 2 is ar=1,200 and month 5 is ar^4=9,600, dividing gives r^3=8, so r=2. Therefore a=1,200÷2=600 units.
- A600 unitsCorrect
- B750 units
- C800 units
- D900 units
Explanation
In a geometric sequence, the nth term is given by a × r^(n-1). For month 2: ar = 1,200 and for month 5: ar^4 = 9,600. Dividing: ar^4 / ar = 9,600/1,200, so r^3 = 8 and r = 2. Substituting back: a × 2 = 1,200, therefore a = 600 units. The distractor 750 results from incorrectly calculating r^3 = 12.8.
Did you get it right without looking?
One question tells you little. A timed set on Sequence and Series shows your real accuracy, how long you take and where you lose marks.
More Sequence and Series questions
- What is the value of the sum 1×2 + 2×3 + 3×4 + ... + 10×11?
- The sum of the first n terms of a series is given by Sn = 3n² + 2n for every n. What is the 10th term of the series?
- An investment portfolio generates returns following an infinite geometric series. The first-year return is ₹50,000 and each subsequent year'…
- The sum to infinity of a GP is 12 and its first term is 3. What is the second term of the GP?
- A manufacturing unit's production follows the pattern: 1,200 units in Year 1, 1,500 units in Year 2, 1,800 units in Year 3, and so on. If pr…
- Three positive numbers are in geometric progression. Their sum is 39 and their product is 729. What is the sum of the squares of the three n…