I need this by 11:30pm tonight!! ASAP STATS HOMEWORK
CollegeKid2014
statstest5afa19.docMat 120 – Statistics Test 5
Name: ______________________________ (26 answers, 4 pts ea.)
1. Forbes gave the following data about percentage return on capital for some stocks: 1.9, 2.6, 1.8, 2.6, 2.1, 4.2, 0.6, 0.9, 1.7, 3.4, 2.8, 3.1, 1.0, 0.7, 4.2, 3.2, 4.7, 1.6 (percentage return on capital is normally distributed with s = 1.244%)
Find (round to nearest hundredths):
a. The 98% confidence intervals for the population mean _________________.
b. The 85% confidence intervals for the population mean _________________.
c. How many more (than the original 18) would they need to sample to be 96% sure to be within 0.5 of the population mean? ______________.
2. You live near a Mac Donnel’s and want to estimate the proportion, p, of your neighbors who go there on a typical day.
a. How many people in your neighborhood should you include in your random sampling to be 94% sure that you are within 1% of the population proportion? ___________.
b. If 23 out of 45 of Candiss’ neighbors visit Mac Donnel’s every day, how many people should be included in your random sampling to be 86% sure that you are within 2% of the population proportion? _________
3. You live near a Mac Donnel’s and want to find the population mean for the number of visits from a neighborhood similar to yours on a typical week.
a. You sample 34 of Davy’s neighbors and get the mean to be 6.8 with pop std dev of 1.7. Find the 97% confidence interval for the population mean of Mac Donnel’s visits. _______________________.
b. You ask 54 of Andrien’s neighbors and find that 32 visit regularly. Find the 82% confidence interval for the population proportion of Mac Donnel’s visitors. _______________________.
4. What is the sample mean if the confidence interval is (127.4 g, 268.1 g)? _________
**for problems 5 & 6, find the zc or tc value, as appropriate.
5. What is zc/tc for a 72% confidence level when the pop std dev is known? ________
6. What is zc/tc for an 88% confidence level when p-hat is 0.35? ________
7. Find the point estimate of the population proportion if 46 out of 92 people prefer the weather of April. _______________
8. Carryon’s new plant makes pistons where the variation in radius must be minimal. You sample 26 pistons and find a standard deviation of 1.18 mm. Assuming the radii to be normally distributed, find:
a.
2
L
C
and2
R
C
for a 80% confidence. __________ and __________b.
2
L
C
and2
R
C
for a 99% confidence. __________ and __________c. The 95% confidence for the population variance. _______________________
For the following, conduct a hypothesis test using the p-value or critical value method.
Find and state: a) H1 or H0, as requested, b) zc or tc value as appropriate c) z or t value as appropriate d) the interpreted answer to the question.
9. The C-Paz Light Bulb Company claims the mean life of a certain type of bulb more than 2500 hours, with a population standard deviation of 400 hours. Mairy’s random sample of 182 bulbs has a mean life of 2515 hours. Does your data support C-Paz’s claim at α = 0.04?
a) H1__________ b) __________ c) __________ d) ________________________________
10. Shutrum University claims the mean class load for their faculty is less than 25 students. Hanha randomly selected 22 classes and record the class size of each. At a 6% level of significance, does the data support SU’s claim? Hanha’s data: 15, 20, 25, 30, 28, 32, 31, 18, 25, 29, 30, 25, 28, 11, 23, 28, 16, 20, 21, 21, 18, 16. (s = 5.965) (MU class size is normally distributed)
a) H0__________ b) __________ c) __________ d) _______________________________
11. Jissica sells real estate. She saw that in a sample of 23 of her homebuyers, 13 found her through a friend. At α = 0.07 can she reject the claim that less than 70% of homebuyers find their real estate agent through a friend?
a) H1__________ b) __________ c) __________ d) _______________________________
