Question #ae78c

1 Answer
May 25, 2017

Andy has to obtain #95%#.

Explanation:

The average is calculated by adding the different grade values and dividing the sum by the number of grades added.

In this case, we have three grades and need to find the fourth, which we shall indicate as #x#.

Since we already have the desired average, we can write:

#(84+65+76+x)/4=80#

#(225+x)/4=80#

Multiply both sides by #4#.

#(225+x)/(1cancel4)xx1cancel4=4xx80#

#225+x=320#

Subtract #225# from each side.

#225-225+x=320-225#

#x=95#