Select the triad in which the numbers are related in the same way as are the numbers of the following triads. (NOTE: Operations should be performed on the whole numbers, without breaking down the numbers into its constituent digits. E.g., 13 – Operations on 13 such as adding/deleting/multiplying etc. to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is not allowed.) (2, 3, 17) (5, 2, 21)
- (a)(3, 4, 23)
- (b)(5, 6, 72)
- (c)(2, 5, 42)
- (d)(1, 4, 17)
Answer
Why
Correct — A. Rule: third = first × second + 11, worked on the whole numbers as the bracketed note requires.
(2, 3, 17): 2 × 3 = 6
6 + 11 = 17
(5, 2, 21): 5 × 2 = 10
10 + 11 = 21
Option (a): 3 × 4 = 12
12 + 11 = 23 → it fits.
Why the others are wrong
- (b)(5, 6, 72) — 5 × 6 = 30 and 30 + 11 = 41, not 72. To reach 72 the constant would have to be 42, which fits neither sample triad.
- (c)(2, 5, 42) — 2 × 5 = 10 and 10 + 11 = 21, not 42 — exactly double. The 21 is borrowed from the second sample triad, which is what makes it look familiar.
- (d)(1, 4, 17) — 1 × 4 = 4 and 4 + 11 = 15, not 17. The 17 is lifted straight from the first sample triad.
Concept
A triad analogy asks for one arithmetic rule mapping the first two numbers onto the third, and it must hold for every sample triad before you touch the options.
Run the combinations in a fixed order — sum, difference, product, quotient — then look for a constant added or subtracted, because a bare operation rarely lands exactly.
Two sample triads are enough: the first offers candidate rules, the second kills all but one.
The bracketed note bars digit-splitting, so 17 is seventeen and never 1 and 7. It reads like boilerplate, but it does real work here — several digit-level rules would otherwise fit the samples.
Key facts
- The rule here is third = first × second + 11, and it holds for both given triads.
- The bracketed note confines every operation to the whole numbers.
- A rule must be verified on every sample triad supplied, not only the first.
Study next
Common traps
- Fitting a rule to the first triad only, then taking the first option that matches it
- Splitting numbers into digits despite the bracketed note
- Abandoning the item when the bare sum, difference and product all fail, without trying a constant
SSC hangs the same bracketed digit-splitting note on every item of this family. This shift carries three more: Reasoning Q.16 (sets), Q.17 (triads, where the rule is ×2 + 1 applied twice) and Q.18 (the odd number pair).
Related PYQs
No directly related past PYQ was found.