Question

a student gets the following grades in his 5 subjects: 87 for calculu; 82 for Physics; 79 for Chemistry; 81 for english; 83 for history. Compute the weighted mean if the weights for the 5 subjects are 5,4,4,3, and 3, repectively

Answer 1

multiply each of the test results by their corresponding weights,
5x87 = 435
4x82 = 328
.
83x3 = 249
add them up.

now add up the weight factors:
5+4+4+3+3 = 19

divide the sum from above by 19

think of it this way:
the 87 for Calculus is like having 5 tests of 87
and 4 tests of 82
etc
Then wouldn't you then have 19 tests?
and you would divide the sum of all those tests by 19

let me know what you got, (I wrote my answer down so I can check with you)

Answer 2

21.68

Answer 3

3.81??

Answer 4

82.68