Question

nisha secured 73,86,78 and 75 marks in four test. what is the least number of marks she can secure in her next test, if she has to have a mean score of 80 mark in five test

Answer 1

Find the sum of 5 tests with a mean of 80:

Mean of 5 tests = 80 marks

Sum of 5 tests = 80 x 5

                         = 400 marks

Find the sum of the score of the 4 tests taken:

Sum of the 4 tests = 73 + 86 + 78 + 75

                              = 312 marks

Find the least marks she must scored on the 5th test:

5th test = 400 - 312

             = 88 marks

Answer: The least marks she must scored for her 5th test is 88 marks.

Answer 2

$\frac{73 + 86 + 78 + 75}{4} = \frac{312}{4} = 78$
80 mark
= 5 × 80 = 400
= 400 - 312= 88
at 5th test he have 88 mark