ShmoopTube
Where Monty Python meets your 10th grade teacher.
Search Thousands of Shmoop Videos
Math Videos 1247 videos
Who wants to be a millionaire? In this video, learn about compound interest, interest rates, and the compound interest formula. You'll be buying th...
ACT Math: Pre-Algebra Drill 5, Problem 2. If a and b are prime numbers, how many factors does ab have?
We don't like knocking people down to size, but we do like simplifying radicals. Join us?
SAT Math 4.1 Statistics and Probability 243 Views
Share It!
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…
Related Videos
SAT Math 2.1 Geometry and Measurement. What is the measure of angle z in terms of x and y?
In 2014, the unemployment rate of one county in California was 7%. In another county, the unemployment rate was 11%. Which of the following express...
Angela is making cookies for a bake sale. She expects each batch of her cookies to sell for $40. It costs her $10 to make one batch of cookies, and...