Devry MATH221 Week 4 Quiz Latest 2021 June

MATH221 Statistics for Decision Making

Week 4 Quiz

Question 1 (CO 3) The speed of cars on a stretch of road is normally distributed with an average 42 miles per hour with a standard deviation of 5.9 miles per hour. What is the probability that a randomly selected car is violating the speed limit of 50 miles per hour?

  0.21

  0.91

  0.09

  0.59

 Question 2(CO 3) A survey indicates that shoppers spend an average of 22 minutes with a standard deviation of 8 minutes in your store and that these times are normally distributed. Find the probability that a randomly selected shopper will spend less than 20 minutes in the store.

  0.22

  0.40

  0.60

  0.50

 Question 3(CO 3) The monthly utility bills in a city are normally distributed with a mean of $128 and a standard deviation of $23. Find the probability that a randomly selected utility bill is between $110 and $130.

  0.783

  0.316

  0.318

  0.217

 Question 4(CO 3) A restaurant serves hot chocolate that has a mean temperature of 175 degrees with a standard deviation of 8.1 degrees. Find the probability that a randomly selected cup of hot chocolate would have a temperature of less than 164 degrees. Would this outcome warrant a replacement cup (meaning that it would be unusual)?

  Probability of 0.91 and would warrant a refund

  Probability of 0.91 and would not warrant a refund

  Probability of 0.09 and would not warrant a refund

  Probability of 0.09 and would warrant a refund

 Question 5(CO 3) The yearly amounts of carbon emissions from cars in Belgium are normally distributed with a mean of 13.9 gigagrams per year and a standard deviation of 9.2 gigagrams per year. Find the probability that the amount of carbon emissions from cars in Belgium for a randomly selected year are between 11.5 gigagrams and 14.0 gigagrams per year.

  0.107

  0.397

  0.603

  0.496

 Question 6(CO 3) On average, the parts from a supplier have a mean of 97.5 inches and a standard deviation of 6.1 inches. Find the probability that a randomly selected part from this supplier will have a value between 85.3 and 109.7 inches. Is this consistent with the Empirical Rule of 68%-95%-99.7%?

  Probability is 0.05, which is inconsistent with the Empirical Rule

  Probability is 0.68, which is inconsistent with the Empirical Rule

  Probability is 0.68, which is consistent with the Empirical Rule

  Probability is 0.95, which is consistent with the Empirical Rule

 Question 7(CO 3) A process is normally distributed with a mean of 104 rotations per minute and a standard deviation of 8.2 rotations per minute. If a randomly selected minute has 128 rotations per minute, would the process be considered in control or out of control?

  Out of control as this one data point is more than two standard deviations from the mean

  In control as this one data point is not more than three standard deviations from the mean

  In control as only one data point would be outside the allowable range

  Out of control as this one data point is more than three standard deviations from the mean

 

Question 8(CO 3) The soup produced by a company has a salt level that is normally distributed with a mean of 5.4 grams and a standard deviation of 0.3 grams. The company takes readings of every 10th bar off the production line. The reading points are 5.8, 5.9, 4.9, 5.7, 5.0, 4.9, 5.5, 5.1, 5.7, 6.1. Is the process in control or out of control and why?

  It is out of control as one data point is more than 2 standard deviations from the mean

  It is in control as the values jump above and below the mean

  It is in control as one data point is more than 2 standard deviations from the mean

  It is out of control as one of these data points is more than 3 standard deviations from the mean

 Question 9(CO 3) The blenders produced by a company have a normally distributed life span with a mean of 8.2 years and a standard deviation of 1.3 years. What warranty should be provided so that the company is replacing about 10% of their blenders sold?

  9.9 years

  9.5 years

  11.2 years

  6.5 years

 Question 10(CO 3) A puck company wants to sponsor the players with the 10% quickest goals in hockey games. The times of first goals are normally distributed with a mean of 8.54 minutes and a standard deviation of 4.91 minutes. How fast would a player need to make a goal to be sponsored by the puck company?

  7.92 minutes

  14.83 minutes

  9.16 minutes

  2.25 minutes

 Question 11(CO 3) A stock’s price fluctuations are approximately normally distributed with a mean of $104.50 and a standard deviation of $23.62. You decide to purchase whenever the price reaches its lowest 20% of values. What is the most you would be willing to pay for the stock?

  $84.62

  $98.52

  $110.48

  $124.38

 Question 12(CO 3) The times that customers spend in a book store are normally distributed with a mean of 39.5 minutes and a standard deviation of 15.9 minutes. A random sample of 30 customers has a mean of 36.1 minutes. Would this outcome be considered unusual, so that the store should reconsider its displays?

  No, the probability of this outcome at 0.121, would be considered usual, so there is no problem

  Yes, the probability of this outcome at 0.879 would be considered unusual, so the display should be redone

  No the probability of this outcome at 0.415 would be considered usual, so there is no problem

  Yes, the probability of this outcome at 0.121, would be considered unusual, so the display should be redone

 Question 13(CO 3) The weights of ice cream cartons are normally distributed with a mean weight of 20.1 ounces and a standard deviation of 0.3 ounces. You randomly select 25 cartons. What is the probability that their mean weight is greater than 20.06 ounces?

  0.748

  0.252

  0.447

  0.553

 Question 14(CO 3) Recent test scores on the Law School Admission Test (LSAT) are normally distributed with a mean of 162.4 and a standard deviation of 15.9. What is the probability that the mean of 8 randomly selected scores is less than 161?

  0.402

  0.465

  0.598

  0.535

 Question 15(CO 3) The mean annual salary for intermediate level executives is about $74000 per year with a standard deviation of $2000. A random sample of 36 intermediate level executives is selected. What is the probability that the mean annual salary of the sample is between $71000 and $73500?

  0.334

  0.933

  0.885

  0.067

 Question 16(CO 3) In captivity, a male lion grows to weight about 420 lbs with a standard deviation of 35 lbs.  A zoo would like to have a lion that is in the largest 25% of male lions based on weight.  How much should a male lion weigh for the zoo to obtain the male lion?

  453.2

  1.000

  443.6

  396.4

 Question 17(CO 3) Chairs from a manufacturer have an average height from the leg to the top of the seat of 19 inches with a standard deviation of 0.5 inches.  How tall would a chair need to be from the assembly line to be among the tallest 10% of chairs?

  19.8 inches

  18.4 inches

  19.6 inches

  19.0 inches

 Question 18(CO 3) The average area of a bedroom in a home is 219 square feet with a standard deviation of 32.5 square feet.  What is the largest a bedroom can be and be among the smallest 25% of bedrooms in a home?

  240.9 sq ft

  208.6 sq ft

  251.5 sq ft

  197.1 sq ft