QNT 275 Final Exam 2017 – Probability Distribution Problems

For the probability distribution of a discrete random variable x, the sum of the probabilities of all values of x must be:

Equal 1

Explanation: A sum of all values in a probability distribution will always add up to 1, period.

The following table lists the probability distribution of a discrete random variable x:

X:  2, 3, 4, 5, 6, 7, 8

P(x): 0.15, 0.29, 0.26, 0.13, 0.09, 0.06, 0.02

The mean of the random variable x is:

First, multiply each value of x by its probability P(x), then add all the values together: (2*0.15) + (3*0.29) + (4*0.26) + (5*0.13) + (6*0.09) + (7*0.06) + (8*0.02)

3.98

The standard deviation of the random variable x, rounded to three decimal places, is:

1.497

The daily sales at a convenience store produce a distribution that is approximately normal with a mean of 1350 and a standard deviation of 144.

 In your intermediate calculations, round z-values to two decimal places.

The probability that the sales on a given day at this store are more than 1405, rounded to four decimal places, is:

Find the z score (observation – mean)/ standard deviation or (1405 – 1350) / 144

0.38194

The probability that the sales on a given day at this store are less than 1305, rounded to four decimal places, is:

(1305 – 1350) / 144

0.3125

The width of a confidence interval depends on the size of the:

margin of error

Explanation: The confidence interval is the bounds of the margin of error in a statistical test.

A sample of size 82 from a population having standard deviation = 52 produced a mean of 255.00. The 95% confidence interval for the population mean:

Use the following interval Confidence interval = m +/- (t(α, N-1)*SEM)

Lower limit: 243.57

Upper limit: 266.43

 
  • Student: Lonny McDowell
  • Textbook: QNT 275 Statistics Fundamentals
  • Course: QNT 275 Final Exam 2017
 

Access Tons More QNT 275 Study Material

The fun doesn't stop here. Make sure to check out our latest content on QNT 275 and statistics.

  1. Multiple Choice Answer Guide
  2. Cumulative Frequency Distribution Problem
  3. Temperatures in Los Angeles Problem
  4. Students with Math Anxiety Problem
  5. Probability Distributions

 

Your browser is out of date. It has security vulnerabilities and may not display all features on this site and other sites.

Please update your browser using one of modern browsers (Google Chrome, Opera, Firefox, IE 10).

X