JAMB 2013 Mathematics · Question 21

The mean of seven numbers is 10. If six of the numbers are 2, 4, 8, 14, 16 and 18, find the mode.

Options

A.6
B.8
C.14
D.2

Answer: B. 8

Explanation written with AI and checked against the answer key

Analyze the question: We know the mean of 7 numbers and six of them. We must find the seventh number, then find the mode. Step 1: Find the total Mean = Sum ÷ Number of items Sum = 10 × 7 = 70 Step 2: Sum of the six known numbers 2 + 4 + 8 + 14 + 16 + 18 = 62 Step 3: Find the seventh number 70 − 62 = 8 Step 4: Find the mode The full set is: 2, 4, 8, 8, 14, 16, 18 The number 8 appears twice, and every other number appears once. So the mode is 8. Check: (2 + 4 + 8 + 8 + 14 + 16 + 18) = 70, and 70 ÷ 7 = 10 ✓ Tip: In "mean and mode" questions, the missing number is usually the one that creates a repeat. Find the missing value using Sum = Mean × Count, then check which value appears most often. Mode = most frequent value.

AI can make mistakes. Report anything that looks wrong.