Assume that on the third exam in a calculus course, the average score over the years has been 72 with a standard deviation 12.You are currently taking the course and there are 25 students in the class?

Assume that on the third exam in a calculus course, the average score over the years has been 72 with a standard deviation 12.You are currently taking the course and there are 25 students in the class?

  1. Given the following sample of 10 high
    temperatures from March:55, 60, 57, 43,
    59, 66, 72, 65, 59, 47.

  1. Determine
    the mean.

  2. Determine the median.

  3. Determine the mode.

  4. Describe the shape of the distribution.

  5. Determine Q1, Q2, Q3 and IQR.

  1. The contingency table shows classification of
    students in a Statistics class.





























From NJ



From PA





GPA at least 3.0



15



5



20



GPA below 3.0



45



35



80





60



40



100


  1. If a student is selected at random, what is the
    probability that he/she is from NJ?

  2. If a student is selected at random, what is the
    probability that he/she has a GPA below 3.0?

  3. If we know that the student is from PA, what is
    the probability that he/she has a GPA of at least 3.0?

  4. If a student is selected at random, what is the
    probability that he/she is from NJ and has a GPA below 3.0.

  5. If a student is selected at random, what is the
    probability that he/she from PA and has GPA of at least 3.0.

  1. Your friend is applying for 4 jobs.The hourly pay rate for the 4 jobs are, $8,
    $12, $15, $20.The probability
    distribution below shows the probability of getting each of these jobs:























Job
Pay Rate,
X



Probability,
P(X)



8



.30



12



.20



15



.40



20



.10


  1. What is the probability that your friend will
    get a job paying at least $15/hour?

  2. What is the expected pay rate for your friend?

  1. It is known that 31% of cars are considered gas
    hogs (i.e. they give less than 15 mpg).
    If we select 20 cars at random:

    1. What is the probability that exactly 4 will be
      gas hogs?

    2. What is the probability the at least 4 but not
      more than 7 will be gas hogs?

    3. How many cars are most likely to be gas hogs?

  2. You ask all 200 students at school how much
    money they have in their pockets.The
    amount ranges from $0 to $130.You determine
    the mean to be $56.40 with standard deviation of $8.40.You believe that the amount is normally
    distributed.

    1. If you pick a person at random, what is the
      probability that he/she has at least $45?

    2. What percentage of the students will have
      between $40 and $50 in their pockets.

    3. If you pick a person at random, what is the
      probability that he/she has either less than $30 or more than $70.

    4. Approximately how many people in the class do
      you expect to have at least $65?

    5. We want to identify the students with top 10.5%
      amounts as “rich”.What is the minimum
      dollar amount the students in this group would need in their pockets.

  3. Assume that on the third exam in a calculus
    course, the average score over the years has been 72 with a standard deviation
    12.You are currently taking the course
    and there are 25 students in the class?



  1. What is the probability that
    the mean score for your class will be greater than 75?

  2. What is the probability that
    the mean score for your class will be between 68 and 70?


  1. A sample of 25 days in summer yields an average
    high temperature of 80 with a standard deviation of 12.

    1. Give a point estimate of the true mean of the
      high temperature.

    2. Find a 99% confidence interval for the average
      high temperature for the summer.

    3. How big a sample do we need if we want to be 90%
      confident of being within 7 degrees of the population mean?

  2. A sample of 100 exams yielded an average grade
    of 82 and standard deviation of 14.Find
    a 95% confidence interval for the average exam grade.

  3. Heights of aliens from Mars are known to be
    normally distributed with a population standard deviation of 9 inches.How big a sample do we need to take if we
    want be 95% confident that our error will not exceed 3 inches?

  4. Preliminary studies have shown that 20% of the
    voters might be willing to vote for Sran for President.

    1. Construct a 90% confidence interval for the
      proportion of voters who would be willing to support Sran.

    2. Before entering the race, Sran would like to conduct
      a poll to check his level of support.How
      big should be the sample be if he wants to be 95% sure that the error is no
      more than 2%?

  5. The average weight of men joining a gym has
    historically been 170 pounds with a standard deviation of 27.The owner feels that the average weight has
    now decreased to less than 165 pounds.
    To support his claim, the owner conducts a sample of 25 men and finds
    their average to be 153.He would like
    to use a significance level of .05 to test his claim.

    1. State the null hypothesis.

    2. State the alternate hypothesis.

    3. Will you use z or t distribution for this
      problem?

    4. Is this a two-tail test or a one-tail test?Draw a normal curve representing the problem.

    5. Determine the critical value.

    6. Determine the rejection region.

    7. Calculate the test statistic.

    8. Would you accept or reject the owner’s
      claim?Explain.

  6. The average score on a certain college entrance
    test has been known to be 240.The dean
    of a university feels that this has changed.
    He conducts a sample of 25 students to test his claim.The sample yields an average of 232 with a
    standard deviation of 25. He would like to use a significance level of .10.

    1. State the null hypothesis.

    2. State the alternate hypothesis.

    3. Will you use z or t distribution for this
      problem?

    4. Is this a two-tail test or a one-tail test?Draw a normal curve representing the problem.

    5. Determine the critical value.

    6. Determine the rejection region.

    7. Calculate the test statistic.

    8. Would you accept or reject the dean’s claim?

  7. A presidential candidate states that she
    currently has exactly 30% of the vote.A
    newspaper thinks that this number is inaccurate.So it conducts a sample 500 voters and finds 175
    people support the candidate.The
    newspaper would like to test its claim using .05 significance level.

    1. State the null hypothesis.

    2. State the alternate hypothesis.

    3. Will you use z or t distribution for this
      problem?

    4. Is this a two-tail test or a one-tail test?Draw a normal curve representing the problem.

    5. Determine the critical value.

    6. Determine the rejection region.

    7. Calculate the test statistic.

    8. Would you accept or reject the newspaper’s
      claim?


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