SSC CGL 2024 Tier-I · 13 September 2024, Shift 1 · General Intelligence and Reasoning · Question 19 of 100

Text as printed on a candidate's response sheet for this shift; answer per SSC's tentative key as marked on that sheet. Solution last reviewed 10 September 2026.

Where this paper and its answers come from

SSC does not publish CGL question papers or a public answer key. The questions and options here are reproduced as printed on a candidate's own response sheet for this shift — the Commission's text, unchanged. Each answer is SSC's tentative key as marked on that sheet; SSC allowed challenges to it and never publishes a final key. The solutions are written by UnlockIAS.

What will come in the place of the question mark (?) in the following equation, if ‘+’ and ‘−’ are interchanged and ‘×’ and ‘÷’ are interchanged? 315 × 15 − 93 + 16 ÷ 7 = ?

(a)4
(b)8
(c)2
(d)12

Answer

Why

Correct — C. Rewrite the whole expression with the swapped signs first, then apply BODMAS to the new line.

Swap + with − and × with ÷:
315 × 15 − 93 + 16 ÷ 7 becomes 315 ÷ 15 + 93 − 16 × 7

Now evaluate, division and multiplication before addition and subtraction:
315 ÷ 15 = 21
16 × 7 = 112
21 + 93 − 112 = 114 − 112 = 2 → option (c)

Why the others are wrong

(a)
4 — 4 contradicts the final subtraction. After the swap, 21 + 93 = 114 and 16 × 7 = 112, and 114 − 112 leaves 2.
(b)
8 — 8 would need the multiplication term to be 106. It is 16 × 7 = 112, so the difference from 114 cannot be 8.
(d)
12 — 12 would need either a running sum of 124 or a product of 102. Neither is available: 315 ÷ 15 + 93 = 114 and 16 × 7 = 112.

Concept

A sign-interchange item is two problems stacked. First a substitution: every printed operator is replaced by its partner. Then an ordinary BODMAS evaluation of the resulting expression.

Do them in that order and write the rewritten line down. Swapping mentally while evaluating is where marks are lost, because the eye keeps reading the operator the paper actually printed.

The interchange is symmetric and simultaneous: × becomes ÷ and ÷ becomes × in the same pass, not one after the other.

Two independent swaps are in play here. Getting one right and the other wrong still produces a whole number, which is why a wrong option can look like a clean answer.

Key facts

After the swap the expression reads 315 ÷ 15 + 93 − 16 × 7.
315 ÷ 15 = 21 and 16 × 7 = 112.
21 + 93 − 112 = 2.
BODMAS applies to the rewritten expression, never to the printed one.

Study next

Sign-interchange items that swap two numbers as well as two signsBalancing-the-equation items, where you choose which signs to insert

Common traps

Swapping one pair of signs and forgetting the other.
Evaluating the rewritten line strictly left to right instead of by BODMAS.
Swapping the numbers around each sign as well as the sign itself.

The identical swap pair is set at 11 Sep 2024, 9:00, Reasoning Q.22 on 14014 × 14 − 10 ÷ 8 + 14, which rewrites to 14014 ÷ 14 + 10 × 8 − 14 = 1067.

Which two pairs trade places changes from paper to paper. At 10 Sep 2024, 16:00, Reasoning Q.19 it is ÷ with − and × with +, on 15 × 9 + 7 ÷ 26 − 13, so read the pairs the stem names before touching the numbers.

Related PYQs

No directly related past PYQ was found.