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dolphi86 [110]
2 years ago
7

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 q

uizzes, exactly how many points will he need to bring up his average up to 90%
Mathematics
1 answer:
nevsk [136]2 years ago
6 0

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 \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 brainly.com/question/25323941

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