SSC CGL 2024 Tier-I · 23 September 2024, Shift 3 · Quantitative Aptitude · Question 1 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.

In a team of seven members, the average age of six of the members is 42 years while the age of the seventh member of the team is 36 years more than the average age of all the seven members taken together. Find the age (in years) of the seventh member of the team.

(a)84
(b)78
(c)80
(d)90

Answer

Why

Correct — A. Six of the members average 42, so those six together carry 6 × 42 = 252 years.

Let the seventh member's age be x. All seven then total 252 + x, and their average is (252 + x)⁄7.

The stem puts the seventh age 36 above that seven-member average:
x = 36 + (252 + x)⁄7

Multiply through by 7: 7x = 252 + 252 + x
6x = 504
x = 84 → option (a)

Check: the seven ages total 336, the average is 336⁄7 = 48, and 48 + 36 = 84.

Why the others are wrong

(b)
78 — 78 is 42 + 36 — the answer you get by measuring the 36-year gap from the six-member average of 42 instead of from the average of all seven. The stem says "all the seven members taken together".
(c)
80 — 80 would make the seven-member total 332 and the average 332⁄7 ≈ 47.43, leaving a gap of only about 32.6 years — short of the 36 the stem demands.
(d)
90 — 90 would make the total 342 and the average 342⁄7 ≈ 48.86, a gap of about 41.1 years. That overshoots 36, so 90 is too large.

Concept

Every average question is a total question wearing a disguise. The only usable move is average × count = sum, because sums add and averages do not.

Here two totals are in play: the six known members (6 × 42 = 252) and the whole team (252 + x). The seventh age appears inside the team average as well as outside it, so x sits on both sides of the equation and has to be collected before you divide.

That self-reference is the entire difficulty of the item; the arithmetic afterwards is one line.

The phrase that decides the question is "all the seven members taken together". Change it to "the other six" and the answer becomes 78, which is sitting in the options.

Key facts

Average × number of items = total, and the total is the only quantity you may add or subtract freely.
Six members averaging 42 years carry a combined age of 252 years.
The seventh member is 84, which lifts the seven-member average to 48.

Study next

Weighted averages when two groups of unequal size are mergedReplacement problems where one member leaves and the average shifts by a stated amountTurning a "more than the average" clause into a single linear equation

Common traps

Reading the 36-year gap against the six-member average of 42, which reads 78 straight off the page.
Multiplying through by 7 but leaving the 36 unscaled: 7x = 36 + 252 + x gives x = 48, which is the seven-member average, not the seventh age.

An average item is a sum item with one unknown, and the variation is where the unknown hides. Two unequal groups merged into a class average is asked at 11 Sep 2024, 16:00, Quant Q.9, and two overlapping halves of a month at 9 Sep 2024, 12:30, Quant Q.9.

Related PYQs

No directly related past PYQ was found.

Topic: Averages — all 40 SSC CGL questions on it, every solved shift.