Z-Significant Test
The most commonly used significance level
What is α=.05?
The formula for a t confidence interval
What is x̄±t*(s/sqrt(n))?
The degrees of freedom of a study that finds a sample of 1200 kids to have a mean test score of 85% and a sample standard deviation of s=5%
What is 1199 kids?
The equation for a 2 sample t interval
(x1-x2)+/-t*sqrt((s1^2/n1)+(s2^2/n2))
The meaning of P being less than alpha
What is the result is statistically significant therefore you can reject the null hypothesis?
The formula for the standard error of a t confidence interval
What is s/sqrt(n)?
The one-sided P-value for a study of how fast turtles walk if the study records the walking speed of 12 turtles and finds a sample mean of 3 mph and a sample standard deviation of 1 mph with a confidence level of 50% Hint: Use Table C
What is .25?
The margin of error for a two sample t confidence interval
t*sqrt((s1^2/n1)+(s2^2/n2))
A study is done that determines the length of geckos to be normally distributed with µ=7in and a standard deviation of 2in. Amanda believes the mean length of geckos is less than 7in and conducts her own study where she randomly measures 40 geckos and finds their mean length to be 6 inches. What is the null hypothesis, alternative hypothesis, P-value, and statistical significance of the P-value at a significance level of α=.05
Ho: µ=7in, Ha: µ<7in, P=.0009, Statistically significant and reject null hypothesis
The sample size that gives a margin of error of at least 2 inches for a study of the length of rhinoceros horns that has a sample mean of x̄=8in and a sample standard deviation of s=1in with a t* value of 6.12.
What is 10 Rhinos?
A study is done that determines the length of geckos to be normally distributed with µ=7in Amanda believes the mean length of geckos is less than 7in and conducts her own study where she randomly measures 10 geckos and finds their mean length to be 6 inches and sample standard deviation to be s=1in. She conducts her study using a confidence level of 95% What is the null hypothesis, alternative hypothesis, P-value, and statistical significance of the P-value at a significance level of α=.05.
Ho: µ=7in, Ha: µ<7in, P=.00575, Statistically significant and reject null hypothesis
A study on the weights of Emperor penguins finds that a sample of 30 penguins from one colony has a mean weight of x1=85lbs with a sample standard deviation of s1=10lbs while a sample of 50 penguins from another colony has a mean of x2=75lbs and a sample standard deviation of s2=15. Find the 95% confidence interval for the difference of these two samples.
CI: (4.28, 15.72)
The time it takes to download a video game is normally distributed with µ=2 hrs and σ=1hr. Dave believes it takes longer than 2 hrs to download a video game and so he randomly downloads 20 video games and finds the average time it takes to download a video game to be 2 hours and 30 minutes. What is the null hypothesis, alternative hypothesis, P-value, and statistical significance of the P-value at a significance level of α=.01.
Ho: µ=2hrs, Ha: µ>2hrs, P=.13, Not statistically significant and can not reject null hypothesis
The upper limit of a 96% confidence interval of a study of the weights of 20 sheep with a sample mean of x̄=200lbs and a sample standard deviation of s=100lbs
What is 249.3 lbs
The time it takes to download a video game has a population mean of µ=2 hrs. Dave believes it takes longer than 2 hrs to download a video game and so he randomly downloads 20 video games and finds the average time it takes to download a video game to be 2 hours and 30 minutes and the sample standard deviation to be s=50 minutes. What is the null hypothesis, alternative hypothesis, P-value, and statistical significance of the P-value at a significance level of α=.01.
Ho: µ=2hrs, Ha: µ>2hrs, P=.00735, Statistically significant and reject null hypothesis
The significance of a study of the effects of sleep on college student test scores if scientists believe that having a good nights sleep causes students to score higher if the scientists took a a sample of 10 college students who did not get a lot of sleep before an exam and found their test scores had a x1=76 and s1=6 and a sample of 10 college students who did get a lot of sleep before an exam and found their test scores had a x2=84 and s2=8. Use a significance level of .05.
Statistically Significant, Reject Null Hypothesis, P=.0108976
The weight of koalas is normally distributed with µ=20 lbs and σ=6lbs. Steve believes the average weight of koalas does not equal 20lbs. He measures the weights of 30 randomly selected koalas and finds their mean weight to equal 18lbs. What is the null hypothesis, alternative hypothesis, P-value, and statistical significance of the P-value at a significance level of α=.05
Ho: µ=20lbs, Ha: µ≠20lbs, P=.0679, Not statistically significant and can not reject null hypothesis
The approximate sample size of a study of the time it takes for people to get ready in the morning if the time it takes people to get ready in the morning has a confidence interval of 15 minutes to 50 minutes with a sample standard deviation of s=1500 seconds and a t* of 3.62
What is 27 people?
The weight of koalas is normally distributed with µ=20 lbs. Steve believes the average weight of koalas does not equal 20lbs. He measures the weights of 30 randomly selected koalas and finds their mean weight to equal 18lbs and a sample standard deviation of 5lbs. What is the null hypothesis, alternative hypothesis, P-value, and statistical significance of the P-value at a significance level of α=.01.
Ho: µ=20lbs, Ha: µ≠20lbs, P=.0366, Not statistically significant and can not reject null hypothesis
The sample size that two samples of the time it takes for students to complete this problem need to have in order for their 93% 2-sample confidence interval to have a margin of error of 15 minutes if one sample of students has a mean of x1=1 hour and a sample standard deviation of s1=30 minutes while a sample of students has a mean of x2=2 hours and a sample standard deviation of s2=1 hour. Use a critical value of t*=1.92
74 students in each sample