Class A has 13 pupils and class B has 30 pupils.
Both classes sit the same maths test.
The mean score for class A is 45.
The mean score for both classes is 66.
What is the mean score (rounded to 1 DP) in the maths test for class B?
(13*45 + 30*66) / (13+30) = ____
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whats the answer to the question
To find the mean score for class B, we need to know the total score of all the pupils in class B. We know that the mean score for class A is 45, so we can calculate the total score for class A by multiplying the mean score by the number of pupils in class A:
Total score for class A = Mean score for class A * Number of pupils in class A
Total score for class A = 45 * 13
Total score for class A = 585
Since we also know the mean score for both classes, we can calculate the total score for both classes by multiplying the mean score by the total number of pupils (which is the sum of the number of pupils in class A and class B):
Total score for both classes = Mean score for both classes * (Number of pupils in class A + Number of pupils in class B)
Total score for both classes = 66 * (13 + 30)
Total score for both classes = 66 * 43
Total score for both classes = 2878
Now, to find the total score for class B, we can subtract the total score for class A from the total score for both classes:
Total score for class B = Total score for both classes - Total score for class A
Total score for class B = 2878 - 585
Total score for class B = 2293
Finally, to find the mean score for class B, we divide the total score for class B by the number of pupils in class B:
Mean score for class B = Total score for class B / Number of pupils in class B
Mean score for class B = 2293 / 30
Mean score for class B ≈ 76.4 (rounded to 1 decimal place)
Therefore, the mean score for class B in the maths test is approximately 76.4.