i can get this problem?

Question

marissa has taken four 100-point tests in math this semester. her mean score is 89%

a. how many points has she scoted altogether on the four tests?

b. what score does she need on test #5 so that the mean of all five scores will be 90%

Answer 1

If she has gotten 89% of the points possible, then she has gotten 0.89 x 100 x 4 or 356.

If she wants to bring her average up to 90% for 5 100 point tests, then she'll need to score 0.90 x 100 x 5, or 450.

To do that she'll need to score 450 - 356, or 94 points on the next exam.

Answer 2

a.
To find the total points you multiply total points possible (100) times the number of tests (4). This gives you 400, which you then multiply by the mean score (.89). This gives you 356. To check that this is right, you take the number of points you think she scored altogether (356) and divide it by the number of points possible (400); this yields a mean score of .89%. Thus you know your answer is right

b.
For this second question you need to set up an equation. Recall that the mean score can be calculated by the number of points scored over the number of points possible. Taking a fifth test means that you are going to add 100 points possible to 400; this gives you a denominator of 500. To the numerator, you must add your variable, x; this gives you a numerator of (356+x). The equation you get is set up like this:
(356+x)/500 = .90 ....
You multiply .90 by 500 and get:
356+x= 450
Subtract 356 from both sides:
x= 94.


Therefore, Marissa must obtain a score of 94 for her to have a mean of .90.


Hope that helped

Answer 3

Mean Is the average, Median in the middle grade and mode is the grade seen most often. so a. is 4 x 89 b. is 89 plus five

Answer 4

subtract