Stat 185 Midterm Practice sheet

We'll have an in class exam next week. Here's some key info:

  1. You should bring a calculator
  2. You'll be able to look up normal probabilities on this table.
  3. You can look up your first name here to find which day you are scheduled to take the exam.

The problems will be very much like the ones below.

  1. Suppose the five point summary for a data set is
    Min1st QMed3rd QMax
    82141163185276
    Draw a box plot of the data from this summary.
  2. The CDC recently released the results of its National Health Interview Survey (NHIS). Data in this report come from the combined 2010-2015 NHIS, a large health survey of the U.S. population random sample of U.S. households. The main objective of NHIS is to monitor the health of the U.S. population. The data matrix below shows the first two rows of a simplified version of some of the data.
    gender age height weight frequency duration
    F405.58115430
    M545.8160660
    1. What type of study is this - observational study or controlled experiment?
    2. Identify the variables in the table and classify them as numerical or categorical.
  3. Compute the mean and standard deviation of the sample $\{9,2,4,5\}$.
  4. The SAT is designed to have a mean of 500 with a standard deviation of 100.
    1. Using the normal distribution rules of thumb, what is the percentile of a score of 700?
    2. Referring to a normal table, what is the percentile score of a score of 640?
  5. Suppose a random sample of 100 people from a population produces an average weight of 165.84 with a standard deviation of 34.44. Use this data to write down a 95% confidence interval for the weights of people in the population.
  6. According to FiveThirtyEight, a recent poll of 1005 adults conducted by Ipsos for Reuters found an approval rating of 56% for Joe Biden. Use this data to construct a 95% confidence interval for Biden's approval rating.
  7. I'd like to construct a poll to determine a confidence interval for Joe Biden's approval rating. If I'd like the margin of error to be $\pm2\%$, how large should my sample size be?