The average scores of the last four tests taken by Mike is 86 marks mean:
( x1 + x2 + x3 + x4 ) / 4 = 86
multiply moth sides by 4
x1 + x2 + x3 + x4 = 86 ∙ 4
x1 + x2 + x3 + x4 = 344
Mike have total 344 marks
When x times Mike get 100 marks awerage will be:
( 344 + x ∙ 100 ) / ( 4 + x ) = 92
multiply moth sides by 4 + x
344 + 100 x = 92 ∙ ( 4 + x )
344 + 100 x = 92 ∙ 4 + 92 ∙ x
344 + 100 x = 368 + 92 x
Subtract 92 x from both sides
344 + 100 x - 92 x = 368 + 92 x - 92 x
344 + 8 x = 368
Subtract 344 from both sides
344 + 8 x - 344 = 368 - 344
8 x = 24
x = 24 / 8 = 3
Proof:
The average scores after 4 + x = 4 + 3 = 7 tests will be:
( x1 + x2 + x3 + x4 + 100 + 100 + 100 ) / 7 =
( 344 + 300 ) / 7 = 644 / 7 = 92
The average scores of the last four tests taken by Mike is 86 marks. To raise the scores to 92 marks, at least how many times does Mike have to get 100 marks in a row?
Please help me to solve this one! Thanks a lot🙏
2 answers
Thanks a lot, it helps me a lot🙏