Question

Ivanna has scored 85, 81, 82, and 94 on her previous four tests. What score does she need on her next test so that her average (mean) is 84 ?

Answer 1

Averages are found by adding up all the pieces and dividing by the number of terms added...

Answer 2

... so (85 + 81+ 82 + 94 + x)/5 = 84 and solve

Answer 3

...solve by multiplying both sides by 5 and then subtracting all the numbers on the left from each side

Answer 4

which is....?

Answer 5

wait why multiply

Answer 6

because 5 is in the denominator (dividing) on the left, so you "undo" that by multiplying.
...there's another method...

Answer 7

whats the other method

Answer 8

ok so i came out with 1710=420????/ what did i do wrong

Answer 9

oh wait is the answer 68?

Answer 10

NEVER mind i got the right answer thanks!

Answer 11

Sorry, I got pulled away, the other method is to keep track of how far above or below 84 each number is:
85 - 84 = 1
81 - 84 = -3
82 - 84 = -2
94 - 84 = 10
Then add up all of these, being careful about negatives = 1 - 3 - 2 + 10 = 6
So Ivanna has 6 extra points, which means she can get 84 - 6 = 78