QQuestionMathematics
QuestionMathematics
Class 10R sat a test. The mean mark for the class was 70%. There are 30 students in the class, 20 of whom are boys. The mean mark for the boys in the test was 62%.
Work out the mean mark for the girls.
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Answer
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Step 1:Let's solve this step by step:
Step 2:: Identify the given information
- Boys' mean mark: $$62\%
- Number of boys: 20
Step 3:: Use the weighted average formula
\frac{(20 \times 62) + (10 \times x)}{30} = 70
We can set up the weighted average equation:
Step 4:: Solve the equation algebraically
20 \times 62 + 10x = 70 \times 30
1240 + 10x = 2100
Step 5:: Isolate x
10x = 2100 - 1240
10x = 860
Step 6:: Calculate the girls' mean mark
x = \frac{860}{10} = 86
Final Answer
The mean mark for the girls is 86\%.
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