If '×' means '−', '−' means '+', '/' means '×', and '+' means '÷', which of the following is correct?
- (a)20 + 4 − 2 × 5 = 10
- (b)15 − 3 + 6 / 2 = 12
- (c)48 / 8 + 3 − 5 × 1 = 15
- (d)10 × 2 − 4 + 8 / 2 = 9
Answer
Why
Correct — B. SSC's key marks option (b), 15 − 3 + 6 / 2 = 12. Worked with the stated meanings, its left side comes to 16, not 12; the note on the key records the gap.
Rule: replace each sign by its meaning, then apply BODMAS.
15 − 3 + 6 / 2 becomes 15 + 3 ÷ 6 × 2
Divide: 3 ÷ 6 = 0.5
Multiply: 0.5 × 2 = 1
Add: 15 + 1 = 16, against the 12 printed in option (b).
Why the others are wrong
- (a)20 + 4 − 2 × 5 = 10 — 20 + 4 − 2 × 5 becomes 20 ÷ 4 + 2 − 5 = 5 + 2 − 5 = 2, not the 10 printed on the right.
- (c)48 / 8 + 3 − 5 × 1 = 15 — 48 / 8 + 3 − 5 × 1 becomes 48 × 8 ÷ 3 + 5 − 1 = 128 + 5 − 1 = 132, far from the 15 printed.
- (d)10 × 2 − 4 + 8 / 2 = 9 — 10 × 2 − 4 + 8 / 2 becomes 10 − 2 + 4 ÷ 8 × 2 = 8 + 1 = 9, which matches its printed 9. SSC's key marks (b) instead; the note on the key records this.
Concept
In a pick-the-true-equation item, rewrite the left side of every option with the new meanings, evaluate it by BODMAS, and compare it with the number on the right.
The table here: × means −, − means +, / means ×, and + means ÷. Division and multiplication come before addition and subtraction, left to right among equals.
An option holds only if its two sides match exactly after the swap.
The arithmetic and the key disagree. The symbol table reads the same in the English and Hindi stems, and option (b) is printed as 15 − 3 + 6 / 2 = 12.
Under that table (b)'s left side is 16. Option (d)'s left side, 10 − 2 + 4 ÷ 8 × 2, comes to exactly its printed 9.
The key, read from the colour-marked cell on the response sheet, sits on (b). The sheet does not say whether it carries the tentative key or the final one.
Key facts
- Under this table 15 − 3 + 6 / 2 becomes 15 + 3 ÷ 6 × 2 = 16.
- 3 ÷ 6 × 2 is worked left to right: 0.5 × 2 = 1.
- An equation option holds only if both sides match after the swap.
Study next
Common traps
- Doing 6 × 2 before 3 ÷ 6: ÷ and × of equal rank run left to right, so 3 ÷ 6 × 2 = 1, not 0.25.
- Evaluating an option with its printed signs: 15 − 3 + 6 / 2 as printed is 15, which is not 12 either.
15 Sep 2025, 12:30, Reasoning Q.24 uses this exact table, × as −, − as +, / as × and + as ÷, and keys 16 / 2 + 4 − 1 × 3 = 6, which does hold: 16 × 2 ÷ 4 + 1 − 3 = 6.
14 Sep 2025, 12:30, Reasoning Q.3 uses a different table: ÷ as +, − as ×, + as − and × as ÷. All four of its options print one left side, 42 × 28 − 30 ÷ 48 + 45, with different totals.
After its swap that left side reads 42 ÷ 28 × 30 + 48 − 45 = 45 + 48 − 45 = 48, the keyed total.
Related PYQs
No directly related past PYQ was found.