In 2019, the amount of money that motorists spent on gas had a normal distribution with a mean of $900 and a standard deviation of $100. Between what two amounts symmetrically distributed about the mean did 70% of motorists spend on gas?

Q: A college professor noted that the grades of his students in an introductory statistics class were…

A:

Q: the scores are normally distributed with a mean of 75 and a standard deviation of 9. What…

A: Note: As per the guidelines, only first three sub-parts (1., 2. and 3.) are solved here. Given data:…

Q: for this set of data, the standard deviation is equal to: 9,8,10,5,5,2,3,6,3

A: Mean:The formula for finding mean is shown below:

Q: College Professors have incomes with a standard deviation that is more than $21,000. A recent study…

A:

Q: A significant number of students completed a Statistics exam, and the final marks had a mean of 70…

A: Answer - A significant number of students completed a Statistics exam, and the final marks had a…

Q: The heights of men, in centimetres, are normally distributed with a mean of 175 and a standard…

A:

Q: 95% of 80 freshman history students scored between 70% and 80% on a take home quiz. If this data is…

A: Given,  n=80 α= (1-0.95) =0.05 Let X denote the score of freshmen. As per t-distribution table, the…

Q: According to Chebyshev's rule, within 10 standard deviations from the mean, lies at least of any…

A: Given Information: According to Chebyshev's rule, within 10 standard deviations from the mean, lies…

Q: A large number of applicants for admission to graduate study in business are given an aptitude test.…

A:

Q: If each score is increased by 25, what will be the mean and standard deviation of the distribution…

A: Given that  The distribution of raw scores on particular achievement test Mean = 500 Standard…

Q: A sociologist found that in a sample of 50 retired men, the average number of jobs they had during…

A: Given that  Sample size=50 , Mean=6.9 Population Standard deviation=2.3

Q: A recent survey found that 61​% of all adults over 50 wear glasses for driving. In a random sample…

A: A recent survey found that 61​% of all adults over 50 wear glasses for driving. In a random sample…

Q: A large number of applicants for admission to graduate study in business are given an aptitude test.…

A:

Q: In Melanie's Styling Salon, the time to complete a simple haircut is normally distributed with a…

A: Given, Mean = μ =25SD = σ =4

Q: A candy store sells about 8 million pieces of candy per day with a standard deviation of 300,000…

A: Given : Let X : Number candy that they sell in a given day           μ = 8 million i.e   Mean (μ) =…

Q: The golf scores for a school team were normally distributed with a mean of 68 and a standard…

A: Let X be the golf scores. It is given that X is normally distributed with mean 68 and standard…

Q: For a population with a standard deviation of σ = 5, what is the z-score corresponding to a score…

A: We have to find z score..

Q: An instructor in a large lecture class found, at the end of the semester, that the total point…

A: The provided information is:

Q: In a normally distributed data set of how long customers stay in your store, the mean is 43.5…

A: Given data Mean μ = 43.5 Standard deviation σ = 3.9 95% of your customers to stay in your store.…

Q: In general, the larger the animal the longer the length of pregnancy. For the horse, for example,…

A: A z-score represents the position of a data point in terms of its distance from the mean when…

Q: If a distribution of test scores is normal, with a mean of 78 and a standard deviation of 11, what…

A: Let X be a test score. Then, X ~N(78,112). Then, X~N(78,112)⇒Z=X-7811~N(0,1) a.) P[ Test score is…

Q: If the weekly grocery expenditure of households in a certain urban market is known to be normally…

A:

Q: The typical college freshman spends an average of ?=150 minutes per day, with a standard deviation…

A: Solution: Let X be the time on social media. From the given information, X follows normal…

Q: The scores on the final exam in a statistics course are close to being normally distributed. The…

A: Normal distribution: It is a continuous probability distribution, that is bell-shaped with lighter…

Q: Which is better a score of 95 on a test with a mean of 70 and a standard deviation of 15, or a score…

A:

Q: A recent study found that 69% of all adults over 50 wear sunglasses for driving. In a random sample…

A: Formula : Mean = np Standard Deviation  :

Q: Suppose that the heights of 4-year old boys are normally distributed with a mean of 103cm and a…

A: Let X be the random variable from normal distribution with mean (μ) = 103 cm and standard deviation…

Q: A quantitative data set has a size of 50. At least how many observations lie within seven standard…

A: Suppose X is a random variable with expectation, μ and standard deviation, σ. Then, for any positive…

Q: THE SCORES ON THE SAT MATH HAD A MEAN OF 431 AND A STANDARD DEVIATION OF 117. What percent of…

A:

Q: The average income of a graduate from the University of Eastern West Virginia is $50,000 per year,…

A: X follows a Normal distribution with mean = 50000 and S.D = 2500 Then z=(x-mean)/SD =…

Q: During one season of racing at the Talladega Superspeedway, the mean speed of the cars racing there…

A:

Q: Statewide, the population as a whole watches 6.2 hours of TV per day. A random sample of 1017 senior…

A: Given data is appropriate for testing of hypothesis to test z-test for single mean because it is a…

Q: The height of men in the United states fits with a normal distribution with a mean of 70 inches and…

A:

Q: On the past mathematics test, the bottom 20% of students failed to pass the test. The mean for the…

A: The mean of the data is μ=55 and the standard deviation is σ=11 It is also given that 20% of…

Q: For a recent 10k​ run, the finishers are normally distributed with mean of 56 minutes and a standard…

A: Given data,μ=56σ=13P(45<X<70)=?

Q: A student scored 66 on a general science test where the class mean and standard deviation were 82…

A:

Q: The scores of 800 students in a 100-item exam resemble a normal distribution with a mean of 78 and a…

A: Let X be the random variable from Normal distribution with mean (µ) = 78, standard deviation (σ) = 8…

Q: The scores on a psychology exam were normally distributed with a mean of 59 and a standard…

A: Mean = 59 Standard deviation = 10 The formula for z is: z=x-μσ

Q: in a test of a lifelong brand of tires , a survey revealed that the mean life was 35,000 mikes and…

A: Let the random variable X be the life of tires.  The random variable X follows Normal distribution…

Q: The lengths of pregnancies in a small rural village are normally distributed with a mean of 263 days…

A:

Q: A biologist found the wingspans of a group of monarch butterflies to be normally distributed, with a…

A: Given,Mean (μ) = 52.2Standard deviation (σ) = 2.3a) Required probability is…

Q: An analyst found that the average amount of money in bank accounts at his/her bank is $2,000 with a…

A:

Q: The College Board National Office recently reported that in 2011-2012, the547,038 high school…

A: The given information is:

Q: Jessica, the owner of a medium-scale native handicrafts shop, knows from experience that the time…

A:

Q: According to the Department of Education the mean number of hours college students spend studying…

A:

Q: An instructor in a large lecture class found, at the end of the semester, that the total point…

A: It is given that mean and standard deviation are 530 inches and 80, respectively.

Q: Interpret the ­z-score of 1.45 in terms of its relationship to standard deviation as well as the…

A: Solution: From the given information, z=1.45.

Q: The scores for all high school seniors taking the verbal section of the Scholastic Aptitude Test…

A: Given distribution is bell shaped. In bell shaped distribution mean, median and mode are equal.…

Q: The variance in a data set is 427. Find the standard deviation. Round to two decimals.

A: The random variable is X. It is given that the variance is 427. We have to find the standard…

Confidence Intervals

When we calculate intervals in probability and statistics, it can be simply termed as finding out a confidence interval. The confidence interval is usually calculated from the data set which is observed. The value of the parameter that needs to be calculated is present here only.