Kelly sells used iPhones what is 40% above what they paid how much did Kelly pay for the iPhone that she is selling for $448

The manager of a grocery store has taken a random sample of 100 customers. The average length of time it took these 100 customer

AlladinOne [14]

Answer:

$4-2.326\frac{1}{\sqrt{100}}=3.767$

$4+2.326\frac{1}{\sqrt{100}}=4.233$

So on this case the 98% confidence interval would be given by (3.767;4.233)

Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

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".

$\bar X=4$ represent the sample mean

$\mu$ population mean (variable of interest)

$\sigma=1$ represent the population standard deviation

n=100 represent the sample size

Solution to the problem

The confidence interval for the mean is given by the following formula:

$\bar X \pm z_{\alpha/2}\frac{\sigma}{\sqrt{n}}$ (1)

Since the Confidence is 0.98 or 98%, the value of $\alpha=0.02$ and $\alpha/2 =0.01$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-NORM.INV(0.01,0,1)".And we see that $z_{\alpha/2}=2.326$

Now we have everything in order to replace into formula (1):

$4-2.326\frac{1}{\sqrt{100}}=3.767$

$4+2.326\frac{1}{\sqrt{100}}=4.233$

So on this case the 98% confidence interval would be given by (3.767;4.233)

4 0

3 years ago

I need help! Please! Geometry! I don't know what I'm doing!

Ber [7]

Hi! collinear means on the same line, while coplanar means on the same plane! here’s what i got for these questions:

2 - false

4 - i’m not too sure on this one, but i believe it’s true!

6 - false

7 - true

try to check the answers and make sure they’re true before submitting! hope this helped!:)

8 0

3 years ago

Kevin and Randy Muise have a jar containing 92 coins, all of which are either quarters or nickels. The total value of the coins

Artemon [7]

<span>Let n = the number of nickles
Let q = the number of quarters
Then for your problem we have
(1) n + q = 43 and
(2) 5*n + 25*q = 100*6.95 (always work in cents to avoid decimal numbers) or
(3) 5*n + 25*q = 695
Now substitute n of (1) into (3) and get
(4) 5*(43 - q) + 25*q = 695 or
(5) 215 - 5*q + 25*q = 695 or
(6) 20*q = 695 - 215 or

(7) 20*q = 480 or
(8) q = 24
Then using (1) we get
(9) n + 24 = 43 or
(10) n = 19
Let's check these values.
Is (.05*19 + .25*24 = 6.95)?
Is (.95 + 6.00 = 6.95)?
Is (6.95 = 6.95)? Yes
Answer: Kevin and Randy have 19 nickles and 24 quarters in the jar.</span>

7 0

3 years ago

What is the measure of x? Please help!

Zepler [3.9K]

Answer:

x =√[y²+(27)²] = √[ z² - 3² +(27)²]

Step-by-step explanation:

step 1) x=√[y²+(27)²]

step 2)

We find y

z²=y²+3² → y² = z² - 3²

step 3) x = √[ z² - 3² +(27)²]

7 0

3 years ago

What's 5m²+5m+9m+8m²-m²= plss

NISA [10]

Answer:

12m^2+14m

Step-by-step explanation:

The "^means exponet" Hope I made your day

:)

6 0

3 years ago

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