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3 years ago

A bricklayers union charges monthly dues of $3 plus $.18 for each hour worked during

Mathematics

1 answer:

Radda [10]3 years ago

7 0

Answer:

160 hours

Step-by-step explanation:

y=3+.18(hours)

31.80=3+.18(hours)

28.8=.18(hours)

160=hours

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Student scores on exams given by a certain instructor have mean 74 and standard deviation 14. This instructor is about to give t

Lapatulllka [165]

Answer:

$P(\bar X >80)=P(Z>2.143)=1-P(z$

Step-by-step explanation:

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

Let X the random variable that represent the Student scores on exams given by a certain instructor, we know that X have the following distribution:

$X \sim N(\mu=74, \sigma=14)$

The sampling distribution for the sample mean is given by:

$\bar X \sim N(\mu,\frac{\sigma}{\sqrt{n}})$

The deduction is explained below we have this:

$E(\bar X)= E(\sum_{i=1}^{n}\frac{x_i}{n})= \sum_{i=1}^n \frac{E(x_i)}{n}= \frac{n\mu}{n}=\mu$

$Var(\bar X)=Var(\sum_{i=1}^{n}\frac{x_i}{n})= \frac{1}{n^2}\sum_{i=1}^n Var(x_i)$

Since the variance for each individual observation is $Var(x_i)=\sigma^2$ then:

$Var(\bar X)=\frac{n \sigma^2}{n^2}=\frac{\sigma}{n}$

And then for this special case:

$\bar X \sim N(74,\frac{14}{\sqrt{25}}=2.8)$

We are interested on this probability:

$P(\bar X >80)$

And we have already found the probability distribution for the sample mean on part a. So on this case we can use the z score formula given by:

$z=\frac{\bar X -\mu}{\frac{\sigma}{\sqrt{n}}}$

Applying this we have the following result:

$P(\bar X >80)=P(Z>\frac{80-74}{\frac{14}{\sqrt{25}}})=P(Z>2.143)$

And using the normal standard distribution, Excel or a calculator we find this:

$P(Z>2.143)=1-P(z$

6 0

4 years ago

The area of the square is 64 square centimeters. Find the perimeter of the square.

andrey2020 [161]

8*8=64 8 *4(sides) is 32 but that's an equilateral triangle

5 0

4 years ago

Whats the domain and range of y=2x+1

Nataliya [291]

Domain: (−∞,∞)
Range: (−∞,∞)

4 0

3 years ago

What’s 6 - 7/15 in the simplest form

NeX [460]

90/15-7/15=83/15 the correct answer to this equation.

4 0

3 years ago

Sarah will earn $14 per hour at a new job. During training, she will earn $8 per hour. What percent of Sarah's regular hourly ra

inessss [21]

Answer:

It depends on how many hours she trains for..

Step-by-step explanation:

For example, if she trains for 2 hours, she will get $16, and if she trains for 3 hours, she will get $24. It goes on like that.

8 0

3 years ago