The mean of a list of test scores is 80. Adding

Ответ:

adore81i

21.01.2022

Step-by-step explanation:

The mean of a list of test scores is 80

Adding an additional test score of 92 caused the mean to rise to 82

To find:

After this additional, how many total test are in the list ?

Solution:

Let the total number of test at first =

And sum of total score =

As we know, mean = $\frac{sum \ of \ total \ observation}{number\ of \ total\ observation}$

$80= \frac{S}{n} \\$

Multiplying both sides by

80n=S

Now, as adding an additional test score of 92 caused the mean to rise to 82,

$S+92=82\times(n+1)\\80n +92 = 82n+82 \ (given \ S =80n)$

$80n-82n =82-92\\-2n=-10$

By dividing both sides by minus ( - )

2n =10

By dividing both sides by 2

n =5

Thus, total number of test at first = = 5

And, after this additional score added, total number of tests are n+1=6

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