stats 6

distribution of and S are independent deviation 4. The what are the The distribution of random variable R has deviation 3. If R mean 10 and standard random variable S has mean 7 and standard mean and standard deviation of the distribution R - S ?

Mean 3 and standard deviation 5

Of all the fish in a certain river , 20 percent are salmon . Once a year , people can purchase a fishing license that allows them to catch up to 8 fish . Assume each catch is independent . Which of the following represents the probability of needing to catch 8 fish to get the first salmon ?

( 0.8 )^7 ( 0.2 )

According to a recent survey , 31 percent of the residents of a certain state who are age 25 years or older have a bachelor's degree . A random sample of 50 residents of the state , age 25 years or older , will be selected . Let the random variable B represent the number in the sample who have a bachelor's degree . What is the probability that B will equal 40 ?

(50 40) ( 0.31 )^40 ( 0.69 )^10

A company that ships crystal bowls claims that bowls arrive undamaged in 95 percent of the shipments . Let the random variable G represent the number of shipments with undamaged bowls in 25 randomly selected shipments . Random variable G follows a binomial distribution with a mean of 23.75 shipments and a standard deviation of approximately 1.09 shipments . Which of the following is the best interpretation of the mean ?

. For all possible shipments of size 25 , the average number of undamaged shipments is equal to 23.75

In a certain large population , 20 % of the households have a total annual income of over $ 80,000 . A simple random sample of 4 households is selected . What is the probability that I or more of the households in the survey have an annual income over $ 80,000 ?

0.5904

An experiment was conducted in which planks of wood painted red and green were shown to pigeons to investigate a pigeon's ability to select a certain color . Pigeons accurately select the color of the plank of wood 20 percent of the time . A simulation was conducted in which a trial consisted of a pigeon being shown eight planks of wood and its number of successes being recorded . This process was repeated many times , and the results are shown in the histogram .

0.94

1. At a certain bakery , the price of each doughnut is $ 1.50 . Let the random variable D represent the number of doughnuts a typical customer purchases each day . The expected value and variance of the probability distribution of D are 2.6 doughnuts and 3.6 ( doughnuts ) , respectively . Let the random variable P represent the price of the doughnuts that a typical customer purchases each day . Which of the following is the standard deviation , in dollars , of the probability distribution of P?

1.5√3.6

Data were collected on the ages , in years , of the men and women enrolled in a large sociology course . Let the random variables M and W represent the ages of the men and women , respectively . The distribution of M has mean 20.7 years and standard deviation 1.73 years . The distribution of W has mean 20.2 years and standard deviation 1.60 years . Of all of those enrolled in the course , 54 percent are men and 46 percent are women . What is the mean age of the combined distribution of both men and women in the course ?

20.47 years

In which of the following should the random variable X not be modeled with a geometric distribution ?

In a bag of 30 different colored candies , about 20 % are red . One candy will be selected one at a time without replacement , and its color will be recorded Let X represent the number of candies selected before red is selected

Data were collected on the number of days per week that members visit a certain fitness center The values varied from 0 to 7 , and a distribution of relative frequencies for the values was variable X represent the number of days per week that a member visits . created . Let the random The mean of X is 3.12 . Which of the following statements is the best interpretation of the mean ?

The long - run average resulting from repeated sampling of members of the fitness center will approach 3.12 days per week

In 2014 , 85 percent of households in the United States had a computer . For a randomly selected sample of 200 households in 2014 , let the random variable C represent the number of households in the sample that had a computer . What are the mean and standard deviation of C ?

The mean is 170 households and the standard deviation is 5.05 households

Let the random variable Q represent the number of students who go to a certain teacher's office hour each day . The standard deviation of Q is 2.2 Which of the following is the best interpretation of the standard deviation ?

from On average , the number of students going to an office hour varies from the mean by about 2.2 students .