A store buys 7 sweaters for $42 and sells them for $182. How much profit does the store make per sweater?

The amount people pay for cable service varies quite a bit but the mean monthly fee is $142 and the standard deviation is $29. t

zhuklara [117]

Answer:

a) By the Central Limit Theorem, the mean is $142 and the standard deviation is $0.7488.

b) By the Central Limit Theorem, approximately normal.

c) 0.0901 = 9.01% probability that the average cable service paid by the sample of cable service customers will exceed $143

Step-by-step explanation:

To solve this question, we need to understand the normal probability distribution and the central limit theorem.

Normal probability distribution

When the distribution is normal, we use the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the zscore of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

Central Limit Theorem

The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean $\mu$ and standard deviation $\sigma$ , the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean $\mu$ and standard deviation $s = \frac{\sigma}{\sqrt{n}}$ .

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

The mean monthly fee is $142 and the standard deviation is $29.

This means that $\mu = 142, \sigma = 29$

Part a: what are the mean an standard deviation of the sample distribution of x hat show your work and justify your reasoning.

Sample of 1500(larger than 30).

By the Central Limit Theorem

The mean is $142

The standard deviation is $s = \frac{29}{\sqrt{1500}} = 0.7488$

Part b: what is the shape of the sampling distribution of x hat justify your answer.

By the Central Limit Theorem, approximately normal.

Part C: what is the probability that the average cable service paid by the sample of cable service customers will exceed $143?

This is 1 subtracted by the pvalue of Z when X = 143. So

$Z = \frac{X - \mu}{\sigma}$

By the Central Limit Theorem

$Z = \frac{X - \mu}{s}$

$Z = \frac{143 - 142}{0.7488}$

$Z = 1.34$

$Z = 1.34$ has a pvalue of 0.9099

1 - 0.9099 = 0.0901

0.0901 = 9.01% probability that the average cable service paid by the sample of cable service customers will exceed $143

4 0

3 years ago

A neon light flashes five times every 10 seconds. Show that the light flashes 43 200 times in one day.

11Alexandr11 [23.1K]

1 day = 24 hours

1 hour = 60 minutes

1 minute = 60 seconds

60 seconds x 60 minutes = 3,600 seconds per hour

3,600 seconds per hour x 24 hours = 86,400 seconds per day.

The light flashes 5 times every 10 seconds:

5 flashes / 10 seconds = 1 flash every 2 seconds

86,400 seconds / 2 seconds = 43,200 flashes per day.

4 0

3 years ago

Linda read 1/5 of a book on Friday and 2/7 of the book on Saturday. On Sunday she read 5/9 of the remaining pages. What fraction

insens350 [35]

Here, you just want to solve it by finding a common denominator.
1/5+2/7, because she read 1/5 and 2/7 of the book on separate days. The common denominator is 35.
7/35+10/35
=17/35
So that's how much of the book she read before Saturday.
Now it says that on Sunday she read 5/9 of the remaining pages, meaning:
1-17/35 should give us our answer
35/35-17/35=18/35
But since it says she read 5/9 of the remaining pages, we need to multiply 18/35 by 5/9 to get what 5/9ths of 18/35 is.
(18/35)(5/9)=2/7
Therefore she read 2/7ths of the book on Sunday.

3 0

3 years ago

Find the solution of the differential equation dy/dt = ky, k a constant, that satisfies the given conditions. y(0) = 50, y(5) =

irga5000 [103]

Answer: The required solution is $y=50e^{0.1386t}.$

Step-by-step explanation:

We are given to solve the following differential equation :

$\dfrac{dy}{dt}=ky~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~(i)$

where k is a constant and the equation satisfies the conditions y(0) = 50, y(5) = 100.

From equation (i), we have

$\dfrac{dy}{y}=kdt.$

Integrating both sides, we get

$\int\dfrac{dy}{y}=\int kdt\\\\\Rightarrow \log y=kt+c~~~~~~[\textup{c is a constant of integration}]\\\\\Rightarrow y=e^{kt+c}\\\\\Rightarrow y=ae^{kt}~~~~[\textup{where }a=e^c\textup{ is another constant}]$