In a mathematics test, the mean score of a group of 12 boys is 60, and the mean score of a… — JAMB UTME

In a mathematics test, the mean score of a group of $12$ boys is $60$ , and the mean score of a group of $18$ girls is $70$ . What is the mean score of all $30$ students combined?

66Answer
B
65
C
64
D
67

Answer

The combined mean score of all 30 students is 66.

To find the overall mean score for the entire class, determine the total sum of all test scores and divide by the total number of students. The total score contributed by the boys is

12 \times 60 = 720

, and the total score contributed by the girls is

18 \times 70 = 1260

. The combined total score is

720 + 1260 = 1980

. Dividing this total by

30

students yields a combined mean of

66

Step-by-Step Solution

Calculate the total score for the boys

Total boys' score = 12 × 60 = 720

The sum of data items equals the mean multiplied by the number of items.

Calculate the total score for the girls

Total girls' score = 18 × 70 = 1260

Multiply the number of girls by their mean score.

Find the combined total score and total student count

Combined total score = 720 + 1260 = 1980; Total students = 12 + 18 = 30

Sum the total scores and the total counts for both groups.

Calculate the combined mean score

Combined mean = 1980 / 30 = 66

Divide the combined total score by the total number of students.

Key Concept

Combined Mean of Two Ungrouped Datasets

Question

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Topics

More questions from this topic