Question

on the last 5 quizzes, marco has earned a total of 21 out of 25 possible points. if he has a perfect score on the next several quizzes, exactly how many points will he need to bring up his average up to 90%

Answer 1

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 sum of all observations divided by the number of observations.

In this problem:

• In the first 5 observations, total of 21 out of 25 points, hence the mean for these observations is $\frac{21}{25} = 0.84$.
• In the next n observations, mean of 1.

Hence, the mean is:

$M = \frac{0.84(5) + n}{5 + n} = \frac{4.2 + n}{5 + n}$

We want the mean to be of 0.9, thus:

$M = 0.9$

$\frac{4.2 + n}{5 + n} = 0.9$

$4.2 + n = 0.9n + 4.5$

$0.1n = 0.3$

$n = \frac{0.3}{0.1}$

$n = 3$

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 https://brainly.com/question/25323941