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Elis [28]
3 years ago
8

I need some help with this problem.

Mathematics
1 answer:
ziro4ka [17]3 years ago
6 0

Answer:

B.

Step-by-step explanation:

hope it helps :)

brainliest pls? have a good day/night

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Customers arrive at a movie theater at the advertised movie time only to find that they have to sit through several previews and
sergij07 [2.7K]

Answer:

a) sample size is 40

Step-by-step explanation:

(a)

\sigma=4 minutes

Margin of error, E is 75 seconds E=75/60= 1.25 minutes.

The level of significance \alpha= 0.05 for 95% level of significance

For 95% confidence interval z_{\frac{\alpha}{2}}=1.96 from standard deviation table

Sample size required, n

n=\left (\frac{z_{\frac{\alpha}{2}}\cdot \sigma}{E} \right )^{2}=\left (\frac{1.96\cdot4}{75/60} \right )^{2}=39.337984

Rounding off, n=40

Sample size =40

Keywords:

95% confidence, sample size, Wall Street Journal

3 0
3 years ago
Use benchmarks to estimate 16.8-5.94
Sunny_sXe [5.5K]
The estimated answer is 11. First you round 16.8 to 17 because the decimal is above 5. Then you round 5.94 to 6 because the first decimal place is greater than 5. Lastly you subtract 17 minus 5 to get 11.
7 0
3 years ago
2 Probability and Stats questions!!
mart [117]
 1) To find the confidence interval 
the sample mean x = 38     σ = 9; n = 85;
The confidence level is 95% (CL = 0.95) <span>CL = 0.95
so α = 1 – CL = 0.05   
</span><span>α/2 = 0.025   </span>Z(α/2) = z0.025  
The area to the right of Z0.025 is 0.025 and the area to the left of Z0.025 is 1 – 0.025 = 0.975
Z(α/2) = z0.025 = 1.645 This can be found using a computer, or using a probability table for the standard normal distribution.
<span>EBM = (1.645)*(9)/(85^0.5)=1.6058</span> x - EBM = 38 – 1.6058 = 36.3941 <span> x + EBM = 38 + 1.6058 = 39.6058
</span>The 95% confidence interval is (36.3941, 39.6058).
The answer is the letter D
<span>The value of 40.2 is <span>within the 95% confidence interval for the mean of the sample

</span></span>2) To find the confidence interval  <span>
<span>the sample mean x = </span>76     σ = 20; n = 102; </span><span>
The confidence level is 95% (CL = 0.95) CL = 0.95 
so α = 1 – CL = 0.05   
α/2 = 0.025   Z(α/2) = z0.025 
The area to the right of Z0.025 is 0.025 and the area to the left of Z0.025 is 1 – 0.025 = 0.975 
Z(α/2) = z0.025 = 1.645 This can be found using a computer, or using a probability table for the standard normal distribution.
EBM = (1.645)*(20)/(102^0.5)=3.2575 x - EBM = 76 – 3.2575 = 72.7424 </span>  x + EBM = 76 + 3.2575 = 79.2575 <span> 
The 95% confidence interval is (</span>72.7424 ,79.2575).<span>
The answer is the letter </span>A and the letter D<span>
The value of 71.8 and 79.8 <span> are </span> outside<span> the 95% confidence interval for the mean of the sample</span></span>
5 0
3 years ago
A certain kind of sheet metal has, on average, 3 defects per 18 square feet. Assuming a Poisson distribution, find the probabili
Fofino [41]

Answer:

75.8% probability that a 31 square foot metal sheet has at least 4 defects.

Step-by-step explanation:

In a Poisson distribution, the probability that X represents the number of successes of a random variable is given by the following formula:

P(X = x) = \frac{e^{-\mu}*\mu^{x}}{(x)!}

In which

x is the number of sucesses

e = 2.71828 is the Euler number

\mu is the mean in the given time interval.

In this problem, we have that:

3 defects per 18 square feet.

So for 31 square feet, we have to solve a rule of three

3 defects - 18 square feet

x defects - 31 square feet

18x = 3*31

x = \frac{31*3}{18}

x = 5.17

So \mu = 5.17

Assuming a Poisson distribution, find the probability that a 31 square foot metal sheet has at least 4 defects.

Either it has three or less defects, or it has at least 4 defects. The sum of the probabilities of these events is decimal 1.

So

P(X \leq 3) + P(X \geq 4) = 1

We want P(X \geq 4)

So

P(X \geq 4) = 1 - P(X \leq 3)

In which

P(X \leq 3) = P(X = 0) + P(X = 1) + P(X = 2) + P(X = 3)

P(X = x) = \frac{e^{-\mu}*\mu^{x}}{(x)!}

P(X = 0) = \frac{e^{-5.17}*(5.17)^{0}}{(0)!} = 0.0057

P(X = 1) = \frac{e^{-5.17}*(5.17)^{1}}{(1)!} = 0.0294

P(X = 2) = \frac{e^{-5.17}*(5.17)^{2}}{(2)!} = 0.0760

P(X = 3) = \frac{e^{-5.17}*(5.17)^{3}}{(3)!} = 0.1309

So

P(X \leq 3) = P(X = 0) + P(X = 1) + P(X = 2) + P(X = 3) = 0.0057 + 0.0294 + 0.0760 + 0.1309 = 0.242

Finally

P(X \geq 4) = 1 - P(X \leq 3) = 1 - 0.242 = 0.758

75.8% probability that a 31 square foot metal sheet has at least 4 defects.

8 0
3 years ago
7 3 If you were to graph a line with a slope of 3/2 that intercepts the y-axis at -2 on the coordinate plane, one point on that
pychu [463]

Answer:

4

Step-by-step explanation:

Make a graph.

Start at negative 2 because that's the y intercept. Remember that a minus sign in front of the y intercept just means it's negative.

The slope is basically the rise over the run. How much you go UP divided by how much you run. Since the slope is 3/2, we go up 3 and right 2.

Keep making points and you get 4

3 0
2 years ago
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