Posted by **jasmine** on Saturday, September 24, 2011 at 11:34pm.

the mean of a set of test scores is 64. a new student takes the same test and scores 80 marks. when his score is added to the other scores, the mean increases to 65. how many students sat for the test altogether?

- maths -
**Steve**, Monday, September 26, 2011 at 10:51am
Say there are n scores. If the mean is 64, then the total points is just 64n.

Now, we have one more score, and the mean rises to 65. So, we have n+1 scores with mean 65. And we have added 80 points to the total.

64n+80 = 65(n+1)

64n+80 = 65n+65

n = 15

## Answer this Question

## Related Questions

- statistics - -A set of seven scores has a mean of 10. If one of the scores is ...
- statistics! - 1) Entry to a certain University is determined by a national test...
- Math - 105 91 82 59 97 72 72 88 81 What is the mode of these scores? A.46 B.72 C...
- statistics - 2. Why is it important to know the mean and standard deviation for ...
- statistics - the admissions policy at a certain university requires that ...
- statistics - the admissions policy at a certain university requires that ...
- maths - the mean of the scores of student during the first 5 months is 23.8 ( ...
- Math - The mean of a set of four test scores is 85. If three of the test scores ...
- algebra - tenequal scores have a mean of 30. if one score is doubled, and the ...
- Statistics - Suppose that two different tests A and B are to be given to a ...

More Related Questions