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Jenny's Overall Mean (Not Like That) 290 Views

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Description:

ACT Math: Pre-Algebra: Drill 6, Problem 2. What score must be earned to bring Jenny's overall mean to at least 87?

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Transcript

00:03
You look like you could use a shmoopy question...
00:06
On her first four tests, Jenny earned an 85,
00:08
97, 79, and 84. Her uber-strict parents aren't letting her
00:13
attend the State Math Finals unless she brings her overall mean up to at least 87.
00:19
What must Jenny earn on her next test to be allowed to have... every young girl's dream come true?

00:28
And here are the potential answers...
00:33
OK so what is this question asking?
00:36
Well it's really the advanced ninja version of taking averages.
00:40
Poor Jenny took 4 tests and she's going to take another
00:43
-- she will have taken 5 tests in total.
00:46
And the TOTAL of these 5 tests must have an average of 87 -- or in other words, they
00:51
must total to 5 times 87 or have a total of 435.
00:56
So the answer comes from just adding up the previous 4 tests, subtracting that number
01:02
from 435 and whatever is left is what she has to get to average an 87.
01:11
So if we add the previous 4 tests we get a sub-total of 345.
01:14
Subtract 345 from 435 and we get 90.
01:18
So she has to get a 90 or better on the last test.
01:22
Answer D.
01:23
As in, "Deadly weapons."
Full Transcript