Question

Your grades on three exams are 80, 93, and 91. What grade do you need on the next exam to have an average of 90 on the four exams? sb help

Answer 1

96

Explanation:

Let's assume that the marks needed in the next exam is
`x`. Then if the average becomes 90,

`(80 + 93 + 91 + x)/(4)= 90`

Now we can simply solve for
`x`:

⇒
`(264 + x)/(4)= 90`

⇒
`264 + x = 360` [Multiplying both sides by 4]

⇒
`x = 360 - 264` [Subtracting 264 from both sides]

⇒
`x = \bf96`

Therefore, you need to score 96 in your next exam to have an average of 90 on the four exams.