SSC CGL 2025 Tier-I · 18 September 2025, Shift 1 · General Intelligence and Reasoning · Question 19 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 8 * 2 = 20 and 6 * 3 = 27, then what is 5 * 4 = ?

(a)32
(b)24
(c)36
(d)22

Answer

Why

Correct — C.
Rule: a * b = (a + b) × b

8 * 2 = (8 + 2) × 2 = 10 × 2 = 20 ✓
6 * 3 = (6 + 3) × 3 = 9 × 3 = 27 ✓

5 * 4 = (5 + 4) × 4
= 9 × 4 = 36 → option (c).

Why the others are wrong

(a)
32 — 32 adds 12 to 5 × 4. The amount added is b²: 4 for 8 * 2 and 9 for 6 * 3, so 5 * 4 adds 16 and gives 36.
(b)
24 — 24 is 5 × 4 + 4, adding b once. That fails the first pair: 8 × 2 + 2 = 18, not 20. The rule adds b², not b.
(d)
22 — 22 is 5 × 4 + 2, as if a fixed 2 were added. The given pairs add 4 and then 9, which are 2² and 3², so 5 * 4 adds 4² = 16.

Concept

A symbol-operation item defines the star by examples. Test a candidate rule on every given example before using it.

Here the plain product falls short each time: 8 × 2 = 16 is 4 short of 20, and 6 × 3 = 18 is 9 short of 27. The shortfalls are 2² and 3², so the rule is ab + b², which factorises to (a + b) × b.

Other rules can fit one example and fail the other. a × b + 4 gives 20 for 8 * 2 but 22 for 6 * 3, so both examples must be checked.

Key facts

(a + b) × b = ab + b².
8 * 2 = 10 × 2 = 20 and 6 * 3 = 9 × 3 = 27.
5 * 4 = 9 × 4 = 36.

Study next

Star operations built on a² + b²Star operations where the sum is multiplied by the first number, (a + b) × aStar operations with a constant multiplier, a × b × k

Common traps

Adding b instead of b² to the product, which gives 24
Fitting a rule to 8 * 2 alone: a × b + 4 works there and fails 6 * 3

17 Sep 2025, 09:00, Reasoning Q.20 uses the same pairs, 6 * 3 = 54 and 8 * 2 = 48, but its rule is a × b × 3, so 5 * 4 is keyed 60 there.

15 Sep 2025, 12:30, Reasoning Q.21 multiplies the sum by the first number instead: 5 * 2 = 7 × 5 = 35, and 6 * 4 is keyed 60.

Related PYQs

No directly related past PYQ was found.

Topic: Symbolic/Number Analogy — all 210 SSC CGL questions on it, every solved shift.