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Furkat [3]
3 years ago
15

The mean age at which the population of babies first stand without support is normally distributed with a mean of 13.20 months w

ith a standard deviation of 2.00 months. What is the probability of randomly selecting a sample of 25 children who stood on their own by the average age of 12.2 months or earlier
Mathematics
1 answer:
Veseljchak [2.6K]3 years ago
3 0

Answer:

0.00621

Step-by-step explanation:

We solve the above question using the

Z score formula. This is given as:

z = (x-μ)/σ/√n

where

x is the raw score = 12.20 or earlier

This means x ≤ 12.20

μ is the population mean = 13.20

σ is the population standard deviation = 2

n is the random number of samples = 25

z = 12.2 - 13.2/2/√25

z = -1/2/5

z = -1/0.4

z = -2.5

Probability value from Z-Table:

P(x≤ 12.2) = 0.0062097

Approximately = 0.00621

Therefore, the probability of randomly selecting a sample of 25 children who stood on their own by the average age of 12.2 months or earlier is 0.00621

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Step-by-step explanation:

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2 years ago
Use this information to answer the questions. University personnel are concerned about the sleeping habits of students and the n
Oksanka [162]

Answer:

z=\frac{0.554 -0.5}{\sqrt{\frac{0.5(1-0.5)}{377}}}=2.097  

p_v =P(Z>2.097)=0.018  

If we compare the p value obtained and the significance level given \alpha=0.05 we have p_v so we can conclude that we have enough evidence to reject the null hypothesis, and we can said that at 5% of significance the proportion of  students reported experiencing excessive daytime sleepiness (EDS) is significantly higher than 0.5 or the half.

Step-by-step explanation:

1) Data given and notation

n=377 represent the random sample taken

X=209 represent the students reported experiencing excessive daytime sleepiness (EDS)

\hat p=\frac{209}{377}=0.554 estimated proportion of students reported experiencing excessive daytime sleepiness (EDS)

p_o=0.5 is the value that we want to test

\alpha=0.05 represent the significance level

Confidence=95% or 0.95

z would represent the statistic (variable of interest)

p_v represent the p value (variable of interest)  

2) Concepts and formulas to use  

We need to conduct a hypothesis in order to test the claim that the true proportion is higher than 0.5:  

Null hypothesis:p\leq 0.5  

Alternative hypothesis:p > 0.5  

When we conduct a proportion test we need to use the z statistic, and the is given by:  

z=\frac{\hat p -p_o}{\sqrt{\frac{p_o (1-p_o)}{n}}} (1)  

The One-Sample Proportion Test is used to assess whether a population proportion \hat p is significantly different from a hypothesized value p_o.

3) Calculate the statistic  

Since we have all the info requires we can replace in formula (1) like this:  

z=\frac{0.554 -0.5}{\sqrt{\frac{0.5(1-0.5)}{377}}}=2.097  

4) Statistical decision  

It's important to refresh the p value method or p value approach . "This method is about determining "likely" or "unlikely" by determining the probability assuming the null hypothesis were true of observing a more extreme test statistic in the direction of the alternative hypothesis than the one observed". Or in other words is just a method to have an statistical decision to fail to reject or reject the null hypothesis.  

The significance level provided \alpha=0.05. The next step would be calculate the p value for this test.  

Since is a right tailed test the p value would be:  

p_v =P(Z>2.097)=0.018  

If we compare the p value obtained and the significance level given \alpha=0.05 we have p_v so we can conclude that we have enough evidence to reject the null hypothesis, and we can said that at 5% of significance the proportion of  students reported experiencing excessive daytime sleepiness (EDS) is significantly higher than 0.5 or the half.

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Answer:

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The Blinking Rockets baseball team has had 127,034 visitors to their fan website. Rounded to the nearest ten thousand how many v
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Answer:

Visitors = 130000

Step-by-step explanation:

Given

Visitors = 127034

Required

Approximate to the nearest ten thousand

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7 > 5. So, 1 will be added to 2.

The number of visitors becomes:

Visitors = 130000

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