The mean of 100 observations was calculated as 49. It was later discovered that three observations taken as 40, 20, 50 were actually 60, 70, 80 respectively. The correct mean is

Mean marks of 50 students were found to be 78.4. But later it was detected that 95 was misread as 59 and 25 was misread as 52. What is the difference between correct mean and incorréct mean ?

Consider the following table in respect of students of 4 schools who appeared in a test: School I (60 students, avg 60), School II (50 students, avg 80), School III (50 students, avg 40), School IV (…

If the number of quantities in group A is 10 and in group B is 8, and their individual average is 24 and 16 respectively, find the combined average of the two groups.

The average of three consecutive odd numbers is 43. What is the average of the smallest and largest?

The mean of p, q, r, s and t is 280. If the mean of p, r and t is 240, what is the mean of q and s?