JAMB 2014 Mathematics · Question 4

The mean of 2 - t, 4 + t, 3 - 2t, 2 + t and t - 1 is

Options

A.t
B.-t
C.2
D.-2

Answer: C. 2

Explanation written with AI and checked against the answer key

Analyze the question: The mean of a set of numbers is their sum divided by how many numbers there are. Here there are 5 expressions. Concept: Mean = (sum of all terms) ÷ (number of terms) Solution: Add the five expressions: (2 - t) + (4 + t) + (3 - 2t) + (2 + t) + (t - 1) Constants: 2 + 4 + 3 + 2 - 1 = 10 t terms: -t + t - 2t + t + t = 0 (Check: -1 + 1 = 0, then 0 - 2 = -2, then -2 + 1 = -1, then -1 + 1 = 0.) So the sum = 10 + 0t = 10. Mean = 10 ÷ 5 = 2 Answer: C (2) Tip: In questions like this, add the constants and the variable terms separately. Variable terms often cancel out, which makes the answer a plain number. Be careful with signs, especially terms like -2t.

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