Answer:
The picture is blocked out D:
Step-by-step explanation:
Using the mean concept, it is found that we will need 15 more points to bring up his average up to 90%.
The mean of a data-set is the <u>sum of all observations divided by the number of observations</u>.
In this problem:
- In the first 5 observations, total of 21 out of 25 points, hence the mean for these observations is
. - In the next n observations, mean of 1.
Hence, the mean is:

We want the mean to be of 0.9, thus:





3 more testes are need, each worth 5 points, hence, 15 more points are needed to bring up his average up to 90%.
A similar problem is given at brainly.com/question/25323941
Answer:
x=100
Step-by-step explanation:
Answer:
Sarah is incorrect.
Step-by-step explanation:
By plugging 10 in as 'x' to the equation, we get y=21+(2*10). 2 x 10 is 20, and 20 + 21 is <em>not</em> 42 - it's 41. So, Sarah is incorrect.