Question

Danial's average score after 8 tests is 91%. If he gets a 78% on his next test, what will his new average be?

Answer 1

Solution:

N = 8

Average score after 8 tests = 91%

Total score after 8 tests = average score × N

                                     =91 × 8

                                     = 728

According to question,

N = 9

Average score after next test (i.e 9th test) =?

Total score after 9 tests = 728 + 78 = 806

Again,

Total score after 9 tests = average score × N

806 = Average score × 9

Average score = 806/9

Average score= 89.55%

Thus, Danial's new average will be 89.55%.

Answer 2

Given Danial's average score after

$8$

tests is

$91 \: percentage$

He gets

$78 \: percent$

on his next test, then we need to find the new average.

Given, the average score of Daniel for

$8 \: tests$

From that, we can calculate the sum of the percentages of the marks obtained in 8 tests.

$average = (sum \: of \: \: percentages \: of \: all \: the \: tests )\div \: (total \: number \: of \: tests)$

Here, average is

$91$

Total number of tests is

$8$

Substituting the above values in the formula

$91 =sum \div 8 \\ sum = 91 \times 8 \\ sum = 728$

Therefore sum of the percentages in 8 subjects is

$728$

We are given the percentage of 9th test

$78$

Now, the average of 9 subjects is

$average = total \: sum \div number \: of \: tests \\ average =( 728 + 78) \div 9 \\ average = 806 \div 9 \\ average = 89.55 \: percentag$

Therefore, the new average is

$89.55 \: percentage$

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