The average mark of 10 students in the class is 30 and average mark scored by all other students in the class is 40 if the total number of students are 30. Find the average of the whole class ?

A36.6

B35.5

C55.7

D60.5

Answer:

There are 10 students with an average mark of 30.

Therefore, the total marks scored by these 10 students = 10 × 30 = 300.

Next, we need to identify the second group of students. The total number of students in the class is 30, and 10 students are in the first group. So, the number of 'other students' = 30 - 10 = 20 students.
These 20 students have an average mark of 40. The total marks scored by these 20 students = 20 × 40 = 800.
To find the average of the whole class, we need the total marks of all students and the total number of students.
Total marks of the whole class = Marks from first group + Marks from second group = 300 + 800 = 1100.
Total number of students in the class = 30.
Finally, the average mark of the whole class = (Total marks) / (Total number of students) = 1100 / 30.
When 1100 is divided by 30, the result is 36.666..., which is approximately 36.67 or 36.6 when rounded to one decimal place.

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