Blog

A study is to be done to determine if type of college (public 4-year, private 4-year, community college) and the acceptance of credit cards for tuition payments are independent.  A random sample of colleges is polled and the data is recorded in the table below.   Accepts Credit Cards Does not Accept Credit Cards Public 4 – year 84 16 Private 4 – year 78 35 Community College 103 7 Use this information to complete test for independence at a 0.05 level of significance.  1. What are the null and alternative hypotheses for the test for independence in this situation.       Ho:  [null]      H1: [alt] 2. Find the test-statistic and the p-value for the hypothesis test.       Test-Stat:   [TS]      p-value: [p] 3. What is the initial conclusion?  [initial]  Why? [why] 4.  In the table of expected values, what is the entry for the cell corresponding to Community College and Accepts Cards?  [ans4] 5. Why did this data set meet the criteria for completing the hypothesis test?       All [obs] frequencies are greater than or equal to [five].

94% of community college graduates say that their community college adequately prepared them for upper division course work.  If a random sample of 12 community college graduates is chosen, what is the probability that all of them say that their community college adequately prepared them for upper division course work?   If rounding is necessary, round to 3 decimal places. 

Suppose we were interested in determining if there were differences in the average prices among twolocal supermarkets. We randomly pick the same six items to compare at both supermarkets. Which statisticalprocedure would be best to use for this study?

The histogram below gives the frequency of temperatures recorded in a local city recently. Use the graph to answer the following questions.  1. On how many days was the temperature at least 80? [ans1] 2. What percentage of the days had a temperature below 75? [ans2] 3. What was the lowest temperature?[ans3]

A poll of shoppers at a grocery store was done to determine the amount spent per week on groceries.  The data is summarized in the table below.  Weekly grocery expenditure Number of Customers $50.00 – $59.99 3 $60.00 – $69.99 17 $70.00 – $79.99 22 $80.00 – $89.99 24 $90.00 – $99.99 15 $100.00 – $109.99 2 Use this table to answer the following questions.  1. Estimate the mean and standard deviation for weekly grocery expenditure using this table.      Mean = [mean]  (rounded to two decimal places)      Std dev = [sd]  (rounded to two decimal places) 2. What is the class width of this table?   [width] 3. What is the relative frequency of the second class?  [rel]  (Rounded to three decimal places) 4. What is the best description of the shape of this data set?  [shape]

Find the area under the standard normal curve to the right of z = -1.67.

The table below gives the probability distribution for the number of people in a household in a certain city.  Data Table Number of People  Probability 1 0.267 2 0.336 3 ? 4 0.127 5 0.063 6 0.024 7 0.015 Complete the table by finding P(3), the probability that a household has 3 members.    [answera] Is the random variable, X, continuous or discrete?  [answerb] What is the most likely number people in a household?  If rounding is necessary, round to three decimal places. [answerc] What is the expected number of people in a household?   If rounding is necessary, round to three decimal places [asnwerd] What is the standard deviation in the number of people in a household? If rounding is necessary, round to three decimal places  [answere] Which of the following interpretations of the expected value is correct? [exp]

The probability that an airline flight is delayed is [x].  What is the probability that an airline flight is not delayed? Enter your response rounded to three decimal places in the format 0.XXX.  If you do not use the correct format your response will be considered incorrect. 

A researcher looking into the amount of caffeine in a cup of coffee finds the following summary statistics.  Statistic Amount of caffeine mean 90 mg standard deviation 5.7 mg median 87 mg Q1 77 mg Q3 94 mg Would it be unusual for a cup of coffee to contain 104 mg of caffeine? [yesno] it [would] be unusual for a cup of coffee to contain 104 mg of caffeine because the value is [within] the [interval].

About 56% of all California residents own the home in which they live.  If a random sample of 20 California residents is chosen, find each of the following probabilities.  Round each response to three decimal places.  The probability that exactly 11 of the 20 own the home in which they live.  [ans1] The probability that fewer than 9 of the 20 own the home in which they live. [ans2]