Mr.Fox's fourth grade class of 20 students had an average of 72% on their last test. However, Rose's mark of 76% had been incorrectly recorded as 56 %. What was the correct class average for the test?
A) 82% B) 80% C)73% D) 62%
20*.72 = 14.4
(144+(.76-.56))/20 = .73
so (C)
To find the correct class average for the test, we need to adjust Rose's mark to the correct value and then recalculate the average.
1. Initially, the class average was 72%, so the total marks obtained by all students was 20 * 72 = 1440%.
2. However, Rose's mark was incorrectly recorded as 56% instead of the correct value of 76%. This means there was a difference of 76 - 56 = 20%.
3. To correct this, we need to add 20% to the total marks obtained. So, the correct total marks for the class are 1440 + 20 = 1460%.
4. Now, to find the correct class average, we divide the correct total marks by the number of students. 1460 / 20 = 73%.
Therefore, the correct class average for the test is 73%.
The answer is C) 73%.
To find the correct class average for the test, we need to adjust for the error in Rose's mark.
First, let's calculate the total marks of all the students before the correction. Since there are 20 students and the average is given as 72%, we can calculate the total marks as follows:
Total marks before correction = Average * Number of students
= 72% * 20
= 0.72 * 20
= 14.4
However, Rose's mark was incorrectly recorded as 56% instead of the correct mark, which is 76%. To correct this error, we need to subtract the incorrect mark and add the correct mark to the total marks:
Corrected total marks = Total marks before correction - Incorrect mark + Correct mark
= 14.4 - 56% + 76%
= 14.4 - 0.56 * 20 + 0.76 * 20
= 14.4 - 11.2 + 15.2
= 18.4
Now that we have the corrected total marks, we can find the correct class average:
Correct class average = Corrected total marks / Number of students
= 18.4 / 20
= 0.92
To convert this decimal into a percentage, we multiply this value by 100:
Correct class average = 0.92 * 100
= 92%
Therefore, the correct class average for the test is 92%.
So, the correct answer is not provided among the given options.