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Statistics and Probability Videos 134 videos
SAT Math: Statistics and Probability Drill 1, Problem 2. If the four largest numbers in the set were doubled, what would happen to the median...
SAT Math 1.4 Statistics and Probability. If two standard 6-sided dice are rolled, what is the probability that the sum of the dice will be gre...
SAT Math 1.5 Statistics and Probability. If Silas draws one card, then places it in his pocket and draws another, what is the probability that...
SAT Math 4.1 Statistics and Probability 243 Views
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Description:
SAT Math 4.1 Statistics and Probability
Transcript
- 00:03
Here’s your shmoop du jour, brought to you by Math Tests.
- 00:06
Sometimes, your teachers grade them on a Sine Curve.
- 00:11
On his last four tests, Ted scored a 71, 86, 77, and 92.
- 00:17
What must he score on his fifth test to have an arithmetic mean of at least 85?
- 00:28
He’s looking for the arithmetic mean;
Full Transcript
- 00:30
remember, that's the sum of the data divided by the number of data entries.
- 00:35
It's another name for the AVERAGE.
- 00:43
To find out what Ted must score on his fifth test—we'll call it variable T—to have
- 00:48
an arithmetic mean of at least 85, we can write an equation as follows.
- 00:52
85 equals the sum of all the tests: 71 plus 86 plus 77 plus 92 plus T divided by 5.
- 01:03
Let's solve for T now. We start by multiplying both sides by 5.
- 01:07
We get 85 times 5 is 425. Adding up 71, 86, 77 and 92 equals 326 plus T.
- 01:15
Subtract 326 from both sides...and we get T equals 99.
- 01:20
So 99 is our answer. Yikes. Happy cramming, Ted…
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