Question

Find the mean marks if a student whose marks are 48, is also included.​

Answer 1

Answer:

25

Step-by-step explanation:

Let the 10 students marks be a1​,a2​,...,a10​

Given that average of 10 students marks is 47

Therefore, 47=10a1​+a2​+...+a10​​

⟹a1​+a2​+...+a10​=470 -------(1)

Let the 11th student marks be a11​

Given that average of 11 students is 45

Therefore, 45=11a1​+a2​+...+a10​+a11​​

⟹a1​+a2​+...+a10​+a11​=495 -----(2)

substituting (1) in (2) we get

470+a11​=495

⟹a11​=495−470=25

Therefore, the 11th student marks is 25