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

82.68

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)

21.68

3.81??

To compute the weighted mean of the student's grades, you need to multiply each grade by its corresponding weight, sum up these products, and then divide the sum by the sum of the weights. Here's how you can calculate it:

Step 1: Multiply each grade by its weight:
- Calculus: 87 * 5 = 435
- Physics: 82 * 4 = 328
- Chemistry: 79 * 4 = 316
- English: 81 * 3 = 243
- History: 83 * 3 = 249

Step 2: Sum up the products:
435 + 328 + 316 + 243 + 249 = 1571

Step 3: Calculate the sum of the weights:
5 + 4 + 4 + 3 + 3 = 19

Step 4: Divide the sum of the products by the sum of the weights:
1571 / 19 = 82.68

Therefore, the weighted mean of the student's grades is 82.68.