QUESTION 5

From a sample of 500 college students it was found that 300 of them had taken a statistics course.

Construct a 95% confidence interval for the proportion of college students who have taken a statistics course. What is the LOWER BOUND on the interval? Round your answer to three decimal places (i.e. 0.123).

4 points   

QUESTION 6

From a sample of 500 college students it was found that 300 of them had taken a statistics course.

Construct a 95% confidence interval for the proportion of college students who have taken a statistics course. What is the UPPER BOUND on the interval? Round your answer to three decimal places (i.e. 0.123).

If I toss a fair coin 50,000 times which of the following is true?

a) the number of heads should be between 15,000 and 25,000.

b) the proportion of heads should be close to 50%.

c) the proportion of heads in these tosses is a parameter.

d) the number of heads should be exactly 25,000.

e) the proportion of heads will be close to 1.

When looking at statistics in criminal justice, how do you feel the mean, median, and mode are useful? Do you feel that there are times when one is more valuable than another? How can these be used to help deter crime?

Suppose you are working for a regional residential natural gas utility. For a sample of 95 customer visits, the staff time per reported gas leak has a mean of 219 minutes and standard deviation 34 minutes. The VP of network maintenance hypothesizes that the average staff time devoted to reported gas leaks is 226 minutes. At a 5 percent level of significance, what is the upper bound of the interval for determining whether to accept or reject the VP's hypothesis? Note that the correct answer will be evaluated based on the z-values in the summary table in the Teaching Materials section. Please round your answer to the nearest tenth.

A particular fruit's weights are normally distributed, with a mean of 718 grams and a standard deviation of 27 grams.

If you pick 12 fruits at random, then 16% of the time, their mean weight will be greater than how many grams?

Give your answer to the nearest gram.

1) You test a new drug to reduce blood pressure. A group of 15 patients with high blood pressure report the following systolic pressures (measured in mm Hg): ̄y s before medication: 187 120 151 143 160 168 181 197 133 128 130 195 130 147 193 157.53 27.409 after medication: 187 118 147 145 158 166 177 196 134 124 133 196 130 146 189 156.40 27.060 change: 0 2 4 -2 2 2 4 1 -1 4 -3 -1 0 1 4 1.133 2.295 a) Calculate a 90% CI for the change in blood pressure. b) Calculate a 99% CI for the change in blood pressure. c) Does either interval (the one you calculated in (a) or (b)) include 0? Why is this important? d) Now conduct a one sample t-test using μ = 0, and α = .10. Are the results consistent with (a)? e) Finally, conduct a one sample t-test using μ = 0, and α = .01. Are the results consistent with (b)? PLEASE TELL HOW TO GET ALPHA I USE .05 AND GOT VALUE 2.145

The professors who teach the Introduction to Psychology course at State University pride themselves on the normal distributions of exam scores. After the first exam, the current professor reports to the class that the mean for the exam was 73, with a standard deviation of 7.

a. What proportion of student would be expected to score above 80?

b What proportion of students would be expected to score between 55 and 75?

c. What proportion of students would be expected to score less than 65?

d. If the top 10% of the class receive an A for the exam, what score would be required for a student to receive an A?

e. If the bottom 10% of the class fail the exam, what score would earn a student a failing grade?

using chapter 13 data set 2, the researchers want to find out whether there is a difference among the graduation rates (and these are percentages) of five high schools over a 10-year period. Is there? (hint: are the years a factor?)

To study the effect the ecological impact of malaria, researchers in California measured the effect of malaria on what distance an animal could run in 2 minutes. They used a sample of a local lizard species, Sceloporis occidentalis, collected in the field. They selected 15 lizards from those found to be infected with the malarial parasite Plasmodium mexicanum and 15 lizards found not infected.

The distance each lizard could run in a time limit of 2 minutes was recorded in a controlled environment. The data (below) is also in an Excel file, “Malaria effect”

a) Does this design use paired data or independent samples? Explain.

b) Compute a 95% confidence interval for the difference in distance ran between the two malarial infections of the lizards. Show all of your working.

c) Based on this confidence interval, can you conclude there is a difference in mean distance ran between the infected and uninfected lizards?

d) Conduct a test of significance (at a significance level of 5%) on the difference between infected and uninfected lizards to decide whether the uninfected lizards can run a further distance on average. Follow all steps clearly and write a clear conclusion.

e) Do you have the same conclusion from the confidence interval calculation in c) as that concluded by the test done in d) above? Explain why or why not.

The U.S. Energy Information Administration (US EIA) reported that the average price for a gallon of regular gasoline is $2.94. The US EIA updates its estimates of average gas prices on a weekly basis. Assume the standard deviation is $0.20 for the price of a gallon of regular gasoline and recommend the appropriate sample size for the US EIA to use if they wish to report each of the following margins of error at 95% confidence. (Round your answers up to the nearest whole number.)

(a) The desired margin of error is $0.10. ______

(b) The desired margin of error is $0.06. _________

(c) The desired margin of error is $0.05. ________

FIND P VALUE

T VALUE

CONFIDENCE INTERVAL FOR TESTING MEN HAVE A HIGER BODY TEMP THAN WOMEN

A 95% confidence interval for a population mean was reported to be 148.79 to 155.21. If σ = 15, what sample size was used in this study? (Round your answer to the nearest integer.)

A support used in an automotive application is supposed to have a nominal internal diameter of 1.5 inches. A random sample of 25 brackets is selected and the nominal internal diameter of these brackets is 1.4975 inches. The diameters of the supports are known to be normally distributed with a standard deviation of σ = 0.01 inches.

a) Perform the hypothesis test Ho: μ = 1.5 versus H1 ≠ 1.5 at an α = 0.01 using the 5 hypothesis test steps: 1. Establish the hypotheses

Ho:

H1:

2. Establish the test statistic

3. Establish the rejection zone Rejection Zone:

Graph showing rejection zone (Place the value on the vertical line where the rejection zone begins):

4. Calculate test statistics

5. Establish the conclusion Graph showing rejection zone and placement of test statistics. (Place the value on the vertical line that corresponds to the test statistic):

Based on the previous graph, establish the conclusion that applies to the problem.

b) Determine the p-value (probability of the test statistic) The p-value depends on whether the test is one-tailed or two-tailed. If the hypothesis test is of a tail, then the p-value is the value that comes directly from the probability of the test statistic. If the test is two-tailed, then the p-value is 2 times the probability obtained from looking for the probability of the test statistic

. The value of Ф (1.25) =

The value of α / 2 =

P-value =

c) Based on the p-value and considering an α = 0.01, what would be the decision? Reject or not reject Ho? Use the space to answer.

d) Use the following OC graph to approximate the probability of Type II Error for a true average diameter of 1,495. Start by calculating the value of parameter d with the following formula.

? = ⌈μ − μ0⌉? =

The value of Type II Error is approximately: β =            approximately

The "Power" of the test is: Power = 1 - β = approximately

e) What sample size is required to detect a true average diameter as low as 1,495 inches if we want the “Power” of the test to be 90%? Start by determining how much Error Type II of the “Power” = 1 - β ratio is.

β =

? =

⌈μ − μ0⌉? = n ≈

Central Tendency & Descriptive Statistics:

You have colleagues who reside in different zip codes. Which measure(s) of central tendency (mean, median, mode) or other descriptive statistics would you use to describe this information? (please answer in full paragraph - thank you)

The mean high temperature on the equatorial island of Pacifica is µ = 82 F. For a random sample of 30 days following the eruption of a volcano on another island the mean high temperature on Pacifica was 76 F with standard deviation 8 . Does the data indicate that the mean temperature on Pacifica has changed? Use a 5% significance level.