Binomial Distribution Standard Deviation

Find the standard deviation of a binomial distribution with n=50 and p=0.4 (Round to the nearest tenth)

• 4.2

• 3.5

• 12.0

• 6.2

An algebra 2 test has 6 multiple choice questions with four choices with one correct answer each. If we just randomly guess on each of the 6 questions, what is the probability that you get exactly 3 questions correct?

• 0.962

• 0.132

• 0.831

• 0.250

A test consists of 10 multiple choice questions with five choices for each question.  As an experiment, you GUESS on each and every answer without even reading the questions. 
What is the probability of getting exactly 6 questions correct on this test?

• 0.6%

• 0.00001%

• 0.0064%

• 0.0002%

A test has 8 multiple choice questions with four choices with one correct answer each. If we just randomly guess on each of the 8 questions, what is the probability that you get at least 3 questions correct?

• 0.886

• 0.332

• 0.678

• 0.208

A binomial event has n = 60 trials. The probability of success on each trial is 0.4. Let X be the count of successes of the event during the 60 trials. What are mean X and standard deviation X?

• 24; 3.79

• 24; 14.4

• 4.9; 3.79

• 4.9; 14.4

It is known that about 90% of the widgets made by Buckley Industries meet specifications.  Every hour a sample of 18 widgets is selected at random for testing and the number of widgets that meet specifications is recorded.  What is the approximate mean and standard deviation of the number of widgets meeting

• μ = 1.62; σ = 1.414

• μ = 1.62; σ = 1.265

• μ = 16.2; σ = 1.62

• μ = 16.2; σ = 1.273

X is a binomial random variable with a probability of success of 25%. For 10 trials, what is the standard deviation for the distribution?

Mathematical Equivalence

OFF

32 percent of beach goers end up with some form of sunburn on any given day. Find the standard deviation of a survey of 75 beach goers.

• 16.32

• 17.14

• 1.74

• 24

The American Red Cross says that about 11% of the U.S. population has Type B blood. A blood drive is being held at your school. What is the probability that at least 2 of the first 10 blood donors has Type B blood? 

• 0.088

• 0.697

• 0.214

• 0.303 

When rolling two dice, the probability of rolling doubles is ⅙. Suppose that a game player rolls the dice five times, hoping to roll doubles. What is the probability the player gets doubles less than three times in 5 attempts?

• 0.161

• 0.965

• 0.015

• 0.997