Express your solution as a inequality and use interval notation(Use your logic when giving the interval notation).

Question

Greg has received scores of 79, 84 and 81 on his first three 100 point tests. What score must he get on his fourth 100 point test to keep an average of 86 or greater? Express your solution as a inequality and use interval notation(Use your logic when giving the interval notation).

Answer 1

average = sum of scores/4

for average to be >= 86

sum of scores/4 >= 86

sum of scores >= 344

which means 79 + 84 + 81 + x >= 344

x >= 100