Answer:
[34,54]
Step-by-step explanation:
-The empirical rule states that the 95% of the sampled observations will fall within two standard deviations of the mean for a normally distributed population.
Where:
- 68% is the first standard deviation
- 95% is the second standard deviation about the mean
- 99.7% is the 3rd standard deviation about the mean.
-Therefore. the middle 95% interval is calculated as:
![CI=\mu+2\sigma\\\\=44\pm 2(5)\\\\=44\pm 10\\\\=[34,54]](https://tex.z-dn.net/?f=CI%3D%5Cmu%2B2%5Csigma%5C%5C%5C%5C%3D44%5Cpm%202%285%29%5C%5C%5C%5C%3D44%5Cpm%2010%5C%5C%5C%5C%3D%5B34%2C54%5D)
Hence, the interval is [34,54]
90+30x+30y. This is because the first day, 90 labels were printed, then you will use 30 times x to find how many minutes. This is the same for 30 times y. Youre trying to figure out how many minutes each machine printed for.
Let x = times in the pool
Let y = times in the basketball courts
42=3x+5y
x+y=12
Therefore y = 12-x
Subsitute for y
42 = 3x + 5(12-x)
42 = 3x + 60 -5x
Subtract 60
-18 = -2x
9 = x
The person used the pool 9 times.
To find 4/5 of 20.5 the first step is to convert 4/5 into a decimal. You can do that by dividing 4 by 5.
4/5 is .8 so your equation would now be .8 of 20.5
"of" states that you are multiplying, so .8 times 20.5 is 16.4
4/5 of 20.5 is 16.4
I won't answer them all for you (don't want to cheat - need to learn something).
But for the first one given:
<span>-2x-9y=-25
-4x-9y=-23
you set up either x or y (which ever one you want to eliminate) so that one of them cancels.
So this one is easy - you just have to multiply an entire row by negative (doesn't matter which one) - so that the y's will be + and -
Since they're both 9 and they're subracting NOW - you can eliminate the y value. Now add/subtract the x's. So it'd be -2 or 2 depending on how you eliminated y. Then add the number outside of the = sign. Now just solve for x. After that plug in whatever you got for x into both of the rows. Then find the y value.
Hopefully this wasn't confusing -- reply if it is and I will try to simplify. I can give you contact if you need help with the rest
Good luck!</span>
