SOLUTION: What is the critical value for these? How do I work them out to get the answer? 1. There is an annual hot dog eating contest in Plattsburg, MS and the average number of hot do

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Question 1052291: What is the critical value for these? How do I work them out to get the answer?

1. There is an annual hot dog eating contest in Plattsburg, MS and the average number of hot dogs eaten by one person is 36 with a standard deviation of 6. Find the critical value for a person who can eat more than 2 deviations above the mean.
2. Female high school seniors at a particular school have an average height of 65 inches with a standard deviation of 5 inches. Find the critical value for a female high senior who is less than 1 deviation from the mean.
3. The average weight of a newborn at a particular hospital is 96 ounces with a standard deviation of 3 ounces. Find the critical value for a newborn who is 2 standard deviations below the average weight.
4. A company found that 27 out of 150 of its products were defective after retraining its employees. If the company normally has a 40% defective product rate, find the critical value to determine if retraining the employees helped to minimize the number of defective products.
5. A teacher gives 200 students a study guide for a test and the average score was 90 with a standard deviation of 6. She did not give the other 200 students a study guide and their average score was 70 with a standard deviation of 8. Find the critical value to determine whether or not the study guide helped students to increase their test score.

Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
Area under the standard normal curve relative to a particular z value (crtical value as is referred to here)
the lines referring to the area to the left of those lines:

1) z > 2 , x > 48 hotdogs (36 + 2*6)
2) z < -1, x < 60lb (65 - 1*5)
3) z = -2, x = 90oz (96-2*3)
4) x-bar = 27/150 = .18
z+=blue+%28.18+-+.40%29%2Fsqrt+%28.40%2A.60%2F%28150%29%29
5) z(90-70) = (20 - 0)/[sqrt((6^2/200)+(8^2/200))]
the 0 indicating the idea there is NO significant difference between the means