Question

In: Statistics and Probability

Ian is testing to see if Irvinites eat more fruits and vegetables than the average American....

Ian is testing to see if Irvinites eat more fruits and vegetables than the average American. Previous research indicates that Irvinites eat 5.8 servings per day. The national average is 4.6 with a standard deviation of three. How many people does Josh need in his sample to achieve a power of .80

Solutions

Expert Solution

True mean,   µ =    5.8                              
hypothesis mean,   µo =    4.6                              
                                      
Level of Significance ,    α =    0.05                              
std dev =    σ =    3
power =    0.8                              
ß= 1-power = 0.2                              
δ=   µ - µo =    1.2                              
                                      
Z ( α ) =       1.6449   [excel function: =normsinv(α)                          
                                     
Z (ß) =        0.8416   [excel function: =normsinv(ß)                         
                                      
sample size needed =    n = ( ( Z(ß)+Z(α) )*σ / δ )² = ( (   0.8416   +   1.6449   ) *   3.0   /   1.2   ) ² =   38.6410
                                      
so, sample size =        39   


Related Solutions

People who eat lots of fruits and vegetables have lower rates of colon cancer than those...
People who eat lots of fruits and vegetables have lower rates of colon cancer than those who eat little of these foods. Fruits and vegetables are rich in "antioxidants" such as vitamins A, C, and E. Will taking antioxidants help prevent colon cancer? A medical experiment studied this question with 864 people who were at risk of colon cancer. The subjects were divided into four groups: daily beta-carotene, daily vitamins C and E, all three vitamins every day, or daily...
Dietary guidelines recommend that most people should eat at least seven servings of fruits and vegetables...
Dietary guidelines recommend that most people should eat at least seven servings of fruits and vegetables each day. Yet, research suggests that few Americans do. Researchers suspect that lack of education may be partly to blame. To investigate, you survey 100 people and ask them about their education level and fruit and vegetable intake. Respondents report having 12.5 years of education and eating 4.5 servings of fruits and vegetables a day, on average. The standard deviations for education and fruit...
Laura is testing to see if college students are more stressed out than the normal person...
Laura is testing to see if college students are more stressed out than the normal person is. The mean stress level of the average person is 50 with a known standard deviation of 10. Joseph is going a two-tailed test with α = .10. The null hypothesis is μ = 50. What precisely is μ the mean of? Please choose the correct answer. a.) The mean stress level of college students. b.) The mean stress level of all people. c.)...
Zoe is testing to see if UCI students are more stressed out than the normal person...
Zoe is testing to see if UCI students are more stressed out than the normal person is. The mean stress level of the average person is 50 with a known standard deviation of 10. Amy is going a two-tailed test with α = .10. The null hypothesis is μ = 50. What precisely is μ the mean of? The average UCI student commutes 6.3 miles to school, with a known standard deviation of five miles. Amy believes that social science...
The average American eats 1.5 cups of vegetables a day (may not be accurate). A researcher...
The average American eats 1.5 cups of vegetables a day (may not be accurate). A researcher is interested in whether teenagers eat less vegetables on average than does the average American. She takes a sample of 25 teenagers and asks how much vegetables they eat. She finds that the mean amount of vegetables her subjects eat a day is 1.1 cups with a standard deviation of 0.5. What would be the appropriate test for the researcher to use to test...
The average American eats 1.5 cups of vegetables a day (may not be accurate). A researcher...
The average American eats 1.5 cups of vegetables a day (may not be accurate). A researcher is interested in whether teenagers eat less vegetables on average than does the average American. She takes a sample of 25 teenagers and asks how much vegetables they eat. She finds that the mean amount of vegetables her subjects eat a day is 1.1 cups with a standard deviation of 0.5. What would be the appropriate test for the researcher to use to test...
A diet doctor claims that the average North American is more than 20 pounds overweight. To...
A diet doctor claims that the average North American is more than 20 pounds overweight. To test his claim, a random sample of 20 North Americans was weighed, and the difference between their actual and ideal weights was calculated. The data are listed here. Do these data allow us to infer at the 5% significance level that the doctor’s claim is true? 16 23 18 41 22 18 23 19 22 15 18 35 16 15 17 19 23 15...
A schoolteacher is concerned that her students watch more TV than the average American child. She...
A schoolteacher is concerned that her students watch more TV than the average American child. She reads that according to the American Academy of Pediatrics (AAP), the average American child watches 4 hours of TV per day (μ = 4.0 hours). She records the number of hours of TV each of her six students watch per day. The times (in hours) are 2.7, 4.8, 4.4, 2.4, 4.1, and 5.6. (a) Test the hypothesis that her students watch more TV than...
A schoolteacher is concerned that her students watch more TV than the average American child. She...
A schoolteacher is concerned that her students watch more TV than the average American child. She reads that according to the American Academy of Pediatrics (AAP), the average American child watches 4 hours of TV per day (μ = 4.0 hours). She records the number of hours of TV each of her six students watch per day. The times (in hours) are 4.1, 2.4, 4.8, 5.4, 2.9, and 4.4. 1. Test the hypothesis that her students watch more TV than...
A research center estimates that no more than 30% of college students eat breakfast every day....
A research center estimates that no more than 30% of college students eat breakfast every day. In a random sample of 250 college students say, half of the sample say they eat breakfast every day. At α=0.05, is there enough evidence to reject the researcher's claim?
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT