SSC CGL 2024 Tier-I · 12 September 2024, Shift 3 · General Intelligence and Reasoning · Question 9 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 6 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.

Which number will come in the place of the question mark (?) in the following equation if ‘+’ and ‘−’ are interchanged and ‘×’ and ‘÷’ are interchanged? 49 × 7 − 6 ÷ 2 + 15 = ?

(a)2
(b)5
(c)8
(d)4

Answer

Why

Correct — D. Rewrite the line with both swaps in place, then apply the order of operations to the new line.

Rule: + becomes −, − becomes +, × becomes ÷, ÷ becomes ×, and the numbers stay where they are.

49 × 7 − 6 ÷ 2 + 15 becomes 49 ÷ 7 + 6 × 2 − 15.

49 ÷ 7 = 7
6 × 2 = 12
7 + 12 = 19
19 − 15 = 4 — option (d).

Why the others are wrong

(a)
2 — 2 would need the last step to read 17 − 15. The swapped line puts 19 in front of the subtraction, because 49 ÷ 7 = 7 and 6 × 2 = 12.
(b)
5 — 5 would need 20 − 15. The division and the multiplication in the swapped line are worth 7 and 12, so the running value is 19.
(c)
8 — 8 would need 23 − 15. Division and multiplication are settled before addition and subtraction, which leaves 19 standing before the minus.

Concept

Two separate rules run in sequence here and the order matters. First the symbols are exchanged, which changes the line on the page. Only then does the order of operations apply, and it applies to the rewritten line.

Writing the swapped line out in full before calculating anything costs a few seconds and removes the whole risk. Doing the arithmetic in your head while mentally exchanging symbols is where these marks are lost.

Both swaps are given at once, and each acts on the pair of symbols named. Nothing else about the line changes — the numbers keep their values, their places and their order.

Key facts

After the swap the line reads 49 ÷ 7 + 6 × 2 − 15.
Division and multiplication give 7 and 12, so the line reduces to 7 + 12 − 15.
7 + 12 − 15 = 4.

Study next

Operator-interchange lines where ÷ swaps with − rather than with ×Order of operations on a line carrying all four operators

Common traps

Calculating the printed line first and exchanging the symbols afterwards.
Swapping one named pair of symbols and overlooking the other.
Working the rewritten line strictly left to right, which gives 11 instead of 4.

SSC states the swap in words and prints the equation beside it, varying which two pairs are exchanged. The same instruction runs on 9 Sep 2024, 09:00, Reasoning Q.1 and on 12 Sep 2024, 09:00, Reasoning Q.4.

Related PYQs

No directly related past PYQ was found.