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 (x students, avg 50). If the average marks of the students of all four schools are 58, then how many students appeared from School-IV?

Five years ago, the average age of X₁, X₂, X₃ and X₄ was 50 years. If we include X₅, the present average age of all five is 56 years. Then the present age of X₅ 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 ?

The average marks of 13 papers are 40. Average of first 7 is 42 and last 7 is 35. Marks obtained in the 7th paper are

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

Ramesh scores in five math tests are 89, 75, 78, 84 and 83. What does he need to score in the next test for his final average in all the tests to be at least 82?