A pair of dice is rolled. What is the probability that the sum is 8?

The manager of a supermarket would like to determine the amount of time that customers wait in a check-out line. He randomly sel

garri49 [273]

Complete question:

The manager of a supermarket would like to determine the amount of time that customers wait in a check-out line. He randomly selects 45 customers and records the amount of time from the moment they stand in the back of a line until the moment the cashier scans their first item. He calculates the mean and standard deviation of this sample to be barx = 4.2 minutes and s = 2.0 minutes. If appropriate, find a 90% confidence interval for the true mean time (in minutes) that customers at this supermarket wait in a check-out line

Answer:

(3.699, 4.701)

Step-by-step explanation:

Given:

Sample size, n = 45

Sample mean, x' = 4.2

Standard deviation $\sigma$ = 2.0

Required:

Find a 90% CI for true mean time

First find standard error using the formula:

$S.E = \frac{\sigma}{\sqrt{n}}$

$= \frac{2}{\sqrt{45}}$

$= \frac{2}{6.7082}$

$SE = 0.298$

Standard error = 0.298

Degrees of freedom, df = n - 1 = 45 - 1 = 44

To find t at 90% CI,df = 44:

Level of Significance α= 100% - 90% = 10% = 0.10

$t_\alpha_/_2_, _d_f = t_0_._0_5_, _d_f_=_4_4 = 1.6802$

Find margin of error using the formula:

M.E = S.E * t

M.E = 0.298 * 1.6802

M.E = 0.500938 ≈ 0.5009

Margin of error = 0.5009

Thus, 90% CI = sample mean ± Margin of error

Lower limit = 4.2 - 0.5009 = 3.699

Upper limit = 4.2 + 0.5009 = 4.7009 ≈ 4.701

Confidence Interval = (3.699, 4.701)

5 0

3 years ago

Landon owns a hybrid SUV that can travel 400 miles on a 15 gallon tank of gas. Determine how many miles he can travel in 6 gallo

arlik [135]

Set this up as a proportion.

400/15 = x/6

Solve for x.

I just hope to help! :)

8 0

3 years ago

Can someone please help me and explain to me how to do this geometry problem please? thank you!! ❤

Dennis_Churaev [7]

Measures of angles 2, 3, 4, added equal 180

3 0

3 years ago

The measure of an angle is 8 times the measure of its complement. tina writes an equation and finds the correct measure of each

pogonyaev

One of the unknown angles (let's called it n) has a complement (meaning their sum adds up to 90 degrees) and the other angle is 8 times the unknown angle (8n)

With all this information, you should have the equation:

n + 8n = 90

To solve, combine like terms to get:

9n = 90

Divide by 9 on both sides to isolate the variable n.

n = 10

Now we plug back in to find our angle measurements. The first angle, n, is 10 degrees. The second angle, 8n, is 8 * 10 which is 80; the second angle is 80 degrees.

5 0

3 years ago

A movie collector has 105 movie posters and 90 band posters if she sells 21 movie posters then how many band posters should she

kotykmax [81]

Hi there! :)

Answer:

In order to maintain the same ratio, she should sell 18 band posters.

Step-by-step explanation:

Initial ratio:

Ratio is: 105 movie posters for 90 band posters = 105 : 90

She sells 21 movie posters, which means that we are left with 105 movies minus the 21 she sold.

105 - 21 = 84 → She now has 84 movie posters.

In order to answer your question, you'll need to use the cross product method:

105 movie posters → 90 band posters

84 movie posters → X

(90 × 84) ÷ 105 = X

7,560 ÷ 105 = X

72 = X ⇒ Number of band posters she should have left to maintain the same ratio.

She has 90 band posters :

90 - X = 72

Add "X" to each side of the equation → 72 + X = 72 + X

90 = 72 + X

Subtract 72 from each side of the equation → 90 - 72 = 18

18 = X

There you go! I really hope this helped, if there's anything just let me know! :)

4 0

3 years ago