SSC CGL 2025 Tier-I · 15 September 2025, Shift 1 · General Intelligence and Reasoning · Question 11 of 100

We transcribed this text from the pictures on a candidate's response sheet for this shift; the answer is the key SSC colour-marked on that sheet. Solution last reviewed 13 September 2026.

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If a geometric progression (GP) starts at 3.6 and the common ratio (CR) = 1.5, what is the 3rd term?

(a)7.2
(b)8.1
(c)6.0
(d)6.6

Answer

Why

Correct — B.
Rule: each GP term is the previous term × the common ratio.

1st term = 3.6
2nd term = 3.6 × 1.5 = 5.4
3rd term = 5.4 × 1.5 = 8.1 → option (b)

Check: 3.6 × 1.5² = 3.6 × 2.25 = 8.1.

Why the others are wrong

(a)
7.2 — 7.2 is 3.6 × 2. Two steps of ratio 1.5 multiply by 1.5 × 1.5 = 2.25, not 2.
(c)
6.0 — 6.0 is not a term of this GP. The terms run 3.6, 5.4, 8.1, and 6.0 falls between the 2nd and the 3rd.
(d)
6.6 — 6.6 is 3.6 + 1.5 + 1.5, the 3rd term of an arithmetic progression. In a GP the ratio multiplies; it is not added.

Concept

In a geometric progression each term is the one before multiplied by a fixed number, the common ratio r. The nth term is a × rⁿ⁻¹, where a is the first term.

For the 3rd term, n − 1 = 2, so the first term is multiplied by r twice. The power is one less than the term number because the 1st term has not been multiplied yet.

Multiplying by 1.5 is adding half: 3.6 + 1.8 = 5.4, then 5.4 + 2.7 = 8.1. That does each step without long multiplication.

Key facts

nth term of a GP: a × rⁿ⁻¹.
Here a = 3.6 and r = 1.5, so the terms run 3.6, 5.4, 8.1.
An AP adds a fixed difference, while a GP multiplies by a fixed ratio.

Study next

Sum of the first n terms of a GP: a(rⁿ − 1) ÷ (r − 1)Finding the common ratio from two given termsNumber series that multiply by a fixed ratio

Common traps

Adding the ratio as if it were a common difference, which gives 6.6
Raising r to the term number, 1.5³, instead of one less, 1.5²

The stem gives the first term and the ratio and names the term it wants, so the task is two multiplications. Its wrong options include 6.6, the answer an arithmetic progression with difference 1.5 would give.

Related PYQs

No directly related past PYQ was found.

Topic: Number Series — all 178 SSC CGL questions on it, every solved shift.