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svlad2 [7]
3 years ago
7

Please answer quick!

Mathematics
1 answer:
inessss [21]3 years ago
5 0
The answer should be the 3rd one
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What percent of 70 is 28
solniwko [45]
Find 28/70 and then mult. the result by 100%.

Using a calculator, 28/70 = 0.4.  Multiplying this result by 100%, we get 40%.
3 0
3 years ago
While researching the cost of school lunches per week across the state, you use a sample size of 45 weekly lunch prices. The sta
Drupady [299]

We assume the lunch prices we observe are drawn from a normal distribution with true mean \mu and standard deviation 0.68 in dollars.


We average n=45 samples to get \bar{x}.


The standard deviation of the average (an experiment where we collect 45 samples and average them) is the square root of n times smaller than than the standard deviation of the individual samples. We'll write


\sigma = 0.68 / \sqrt{45} = 0.101


Our goal is to come up with a confidence interval (a,b) that we can be 90% sure contains \mu.


Our interval takes the form of ( \bar{x} - z \sigma, \bar{x} + z \sigma ) as \bar{x} is our best guess at the middle of the interval. We have to find the z that gives us 90% of the area of the bell in the "middle".


Since we're given the standard deviation of the true distribution we don't need a t distribution or anything like that. n=45 is big enough (more than 30 or so) that we can substitute the normal distribution for the t distribution anyway.


Usually the questioner is nice enough to ask for a 95% confidence interval, which by the 68-95-99.7 rule is plus or minus two sigma. Here it's a bit less; we have to look it up.


With the right table or computer we find z that corresponds to a probability p=.90 the integral of the unit normal from -z to z. Unfortunately these tables come in various flavors and we have to convert the probability to suit. Sometimes that's a one sided probability from zero to z. That would be an area aka probability of 0.45 from 0 to z (the "body") or a probability of 0.05 from z to infinity (the "tail"). Often the table is the integral of the bell from -infinity to positive z, so we'd have to find p=0.95 in that table. We know that the answer would be z=2 if our original p had been 95% so we expect a number a bit less than 2, a smaller number of standard deviations to include a bit less of the probability.


We find z=1.65 in the typical table has p=.95 from -infinity to z. So our 90% confidence interval is


( \bar{x} - 1.65 (.101),  \bar{x} + 1.65 (.101) )


in other words a margin of error of


\pm 1.65(.101) = \pm 0.167 dollars


That's around plus or minus 17 cents.




3 0
3 years ago
Read 2 more answers
Rewrite the radical as a rational exponent. the fourth root of 7 to the fifth power
Verdich [7]
7^5/4 would be the answer to the question I think you are asking
7 0
2 years ago
Read 2 more answers
What is the length of GH¯¯¯¯¯¯, to the nearest tenth of a meter? 7.3 m 13.7 m 14.1 m 19.4 m A scalene triangle G H J. The base s
MAVERICK [17]
Using the sine law.
     \frac{GH}{sin\left(45\right)}=\frac{10\:meters}{sin\left(31\right)}

     GH=\frac{10\:meters}{sin\left(31\right)}\cdot sin\left(45\right)=13.7\:m

The measure of side GH is 13.7 meters.
5 0
3 years ago
Read 2 more answers
Subtract 6x^{2}-7x-2 from 6x^{2}-2x+6
sp2606 [1]

Hello!

Let's subtract!

⇒ 6x² - 2x + 6 - (6x² - 7x - 2)

⇒ 6x² - 2x + 6 - 6x² + 7x + 2

⇒ 5x + 8

∴ The difference will be equal to 5x + 8.

8 0
2 years ago
Read 2 more answers
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