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:
150 pi inches or 471.239 inches traveled
Step-by-step explanation:
First, close your eyes, and think about the distance a bike travels after one rotation of the wheel.
You will come to the realization that a full rotation of the wheel makes you travel the circumference of the wheel
The formula for circumference is 2(pi)(r) or (pi)(diameter)
We are given diameter, so let's find distance traveled for one rotation
pi(15 inches) = 15pi inches per rotation.
There are 10 rotations, so:
(15pi inches/rotation)(10 rotations) = 150pi inches travelled
150 x pi = 471.239 inches traveled