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MrRissso [65]
2 years ago
13

Fifty specimens of a new computer chip were tested for speed in a certain application, along with 50 specimens of chips with the

old design. The average speed, in MHz, for the new chips was 495.6, and the standard deviation was 19.4. The average speed for the old chips was 481.2, and the standard deviation was 14.3.Can you conclude that the mean speed of the new chips is greater than that of the old chips?
Mathematics
1 answer:
Murljashka [212]2 years ago
4 0

Answer:

Under 99% confidence level we can say that mean speed of the new chips is greater than that of the old chips

Step-by-step explanation:

H_{0}: Mean speed of the new chip is the same as the old chip

H_{a}: Mean speed of the new chip is greater than the old chip

to calculate the z-statistic we can use the formula:

z=\frac{M_{n}-M_{o}}{\sqrt{\frac{s_{n}^2}{N_{n}} +\frac{s_{o}^2}{N_{o}} } }

if we put the numbers then

z=\frac{495.6-481.2}{\sqrt{\frac{19.4^2}{65}} +\frac{14.3^2}{65} } } =4.8171

The probability of this z-statistic is < 0.001 Therefore Under 99% confidence level we can say that mean speed of the new chips is greater than that of the old chips

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A study was recently conducted at a major university to estimate the difference in the proportion of business school graduates w
sveta [45]

Answer:

(0.1875-0.274) - 1.96 \sqrt{\frac{0.1875(1-0.1875)}{400} +\frac{0.274(1-0.274)}{500}}=-0.1412  

(0.1875-0.274) + 1.96 \sqrt{\frac{0.1875(1-0.1875)}{400} +\frac{0.274(1-0.274)}{500}}=-0.0318  

And the 95% confidence interval would be given (-0.1412;-0.0318).  

We are confident at 95% that the difference between the two proportions is between -0.1412 \leq p_A -p_B \leq -0.0318

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".  

p_A represent the real population proportion for business  

\hat p_A =\frac{75}{400}=0.1875 represent the estimated proportion for Business

n_A=400 is the sample size required for Business

p_B represent the real population proportion for non Business

\hat p_B =\frac{137}{500}=0.274 represent the estimated proportion for non Business

n_B=500 is the sample size required for non Business

z represent the critical value for the margin of error  

The population proportion have the following distribution  

p \sim N(p,\sqrt{\frac{p(1-p)}{n}})  

Solution to the problem

The confidence interval for the difference of two proportions would be given by this formula  

(\hat p_A -\hat p_B) \pm z_{\alpha/2} \sqrt{\frac{\hat p_A(1-\hat p_A)}{n_A} +\frac{\hat p_B (1-\hat p_B)}{n_B}}  

For the 95% confidence interval the value of \alpha=1-0.95=0.05 and \alpha/2=0.025, with that value we can find the quantile required for the interval in the normal standard distribution.  

z_{\alpha/2}=1.96  

And replacing into the confidence interval formula we got:  

(0.1875-0.274) - 1.96 \sqrt{\frac{0.1875(1-0.1875)}{400} +\frac{0.274(1-0.274)}{500}}=-0.1412  

(0.1875-0.274) + 1.96 \sqrt{\frac{0.1875(1-0.1875)}{400} +\frac{0.274(1-0.274)}{500}}=-0.0318  

And the 95% confidence interval would be given (-0.1412;-0.0318).  

We are confident at 95% that the difference between the two proportions is between -0.1412 \leq p_A -p_B \leq -0.0318

7 0
1 year ago
Statements and reasonings 2(4x+2)=20
Katarina [22]

distribute-   8x+4=20

subtract-    8x=20

divide-      20/8=x

answer-   x=2.5


6 0
2 years ago
A spinner has five congruent sections, one each of blue, green, red, orange, and yellow. Yuri spins the spinner 10 times and rec
Burka [1]

Answer:

S = {AB, AC, BC}

Step-by-step explanation:

3 0
1 year ago
Janelle practices basketball every afternoon in the driveway each day her goal is to make four more baskets then she made the da
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She made 62 baskets by day 14. 4×13=52+10=62
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2 years ago
Solve for x. −12 = − 3/4 x A) 6 B) 8 C) 12 D) 16
shepuryov [24]

Answer:

D) 16

Step-by-step explanation:

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