Question

Andy has grades of 84, 65, and 76 on three math tests. What grade must he obtain on the next test to have an average of exactly 80 for the four tests?

Answer 1

(84+65+76+x)/4=80
(225+x)/4=80
225+x=320
x=95

Answer 2

So he needs to score a 95% on his next test.

Answer 3

Hope this helped!

Answer 4

Thanks so much|

Answer 5

Anytime.

Answer 6

can you show the work please

Answer 7

I did

Answer 8

Look at my first reply.

Answer 9

lol can you do it more neater

Answer 10

Absolutly

Answer 11

thanks

Answer 12

The average of four test scores is the sum of the 4 divided by 4, so:

(a + b + c + d) / 4

We have 3 of the 4 scores and want the average to be 80, so:

80 = (84 + 65 + 76 + d) / 4

Solve for d:

320 = 84 + 65 + 76 + d
320 = 225 + d
95 = d

The fourth test score must be a 95 to get an average of 80.

Answer 13

thanks

Answer 14

No problem.

Answer 15

i still dont unnderstand :'

Answer 16

sadly

Answer 17

hmmmmm, I will try to explain it better.

Answer 18

thankss

Answer 19

Anytime

Answer 20

84 is 80 + 4
65 is 80 - 15
76 is 80 - 4

Overall, he is 15 points below 80 over three tests. He has to make up 15 points.

If he makes a 95, his average will be 80.

Answer 21

Better?

Answer 22

omg thanks this helped alot

Answer 23

haha, no problem :)

Answer 24

wait but why is it only 3 numbers

Answer 25

Because the fourth one is the one he needs to get

Answer 26

He has taken 3 tests and needs one more to get the given average.

Answer 27

oh okayy

Answer 28

Well, I have to go help others now, but judging by this problem your in 7th grade right?