Historically, the one-year returns follow approximately the normal distribution. The one-year return for the S&P 500 was +27% (that is, 0.27) and its standard deviation is 20% (that is, 0.2). What is the probability that a stock in the S&P 500 gained 30% or more last year?

(a) 0.0668 (i.e., 6.68%)
(b) 0.4404 (i.e., 44.04%)
(c) 0.5596 (i.e., 55.96%)
(d) 0.9332 (i.e., 93.32%)

What is the probability that a stock in the S&P 500 lost 10% or more last year?

(a) 0.1814 (i.e., 18.14%)
(b) 0.0082 (i.e., 0.82%)
(c) 0.0322 (i.e., 3.22%)
(d) 0.0743 (i.e., 7.43%)

Assume that population mean is to be estimated from the sample described. Use the sample results to approximate the margin of error and​ 95% confidence interval.

Sample​ size,

nequals

100

​;

sample​ mean,

x overbar

equals70.0​cm; sample standard​ deviation,

sequals

5.0cm

Round to one decimal place

The following probability distributions of job satisfaction scores for a sample of information systems (IS) senior executives and middle managers range from a low of 1 (very dissatisfied) to a high of 5 (very satisfied).

(a) What is the expected value of the job satisfaction score for senior executives?

(b) What is the expected value of the job satisfaction score for middle managers?

(c) Compute the variance of job satisfaction scores for executives and middle managers.

executives

middle managers

(d)

Compute the standard deviation of job satisfaction scores for both probability distributions. (Round your answers to two decimal places.)

executives

middle managers

Weights of Northern Pike follow a normal distribution with mean weight of 1.32 pounds and a standard deviation of .6 pounds.

(A). Find the probability a randomly selected pike weights less than 2 pounds.

(B). Find the probability a randomly selected pike weights more than 1 pound?

(C) Find the probability a randomly selected pike weights between 1.2 and 2.2 pounds.

(D)What pike weight corresponds to the 67th percentile?

(E) Suppose you find a random sample of n=16 pike, what is the probability that the sample mean will fall between 1.2 and 2.2 pounds?

A company decided to expand, so it opened a factory, generating 455 jobs.

• For the white-collar positions, 200 males and 200 females applied. Of the females who applied, 20% were hired, while only 15% of the males were hired.
• Of the 400 males applying for blue-collar positions, 75% were hired while 85% of the 100 females who applied were hired.

1. How does looking at the white-collar and blue collar positions separately suggest a preference for hiring women?
2. Do the overall data support the idea that the company hires women preferentially?
3. Explain the apparent inconsistency in these results.

Contaminated water: In a sample of

42

water specimens taken from a construction site,

26

contained detectable levels of lead.

Part 1 of 3

Your Answer is correct

(a) Construct a

90%

confidence interval for the proportion of water specimens that contain detectable levels of lead. Round the answer to at least three decimal places.

A

90%

confidence interval for the proportion of water specimens that contain detectable levels of lead is

0.497<<p0.743

.

Part: 1 / 3

1 of 3 Parts Complete

Part 2 of 3

(b) Construct a

99.8%

confidence interval for the proportion of water specimens that contain detectable levels of lead. Round the answer to at least three decimal places.

Use the following information for this and the next question. In 2019, the mean duration of unemployment for a person is 21.6 weeks. Assume that the population standard deviation is 5 weeks. You would like to conduct a follow-up study, so you select a sample of 40 unemployed people. You need to look into the sampling distribution of the mean number of weeks of unemployment.

What is the mean and standard deviation of that distribution? What is the probability that in a sample of 40 unemployed people, the mean number of weeks of unemployment is within 1 week of the population mean?

A researcher wishes to estimate the proportion of adults who have​ high-speed Internet access. What size sample should be obtained if she wishes the estimate to be within

0.050.05

with

9999​%

confidence if

​(a) she uses a previous estimate of

0.560.56​?

​(b) she does not use any prior​ estimates?

The following data give the average price received by fishermen for several species of fish in 2000 and 2010. The price is in cents per pound.

1. Create a regression equation for the data.
   
   ˆy= (Round to 2 decimal places)
   
2. What is the correlation coefficient between the 2000 and 2010 prices?
   
   _____(Round to 2 decimal places.)
   
3. If a type of fish was 41.3 cents per pound in 2000, how much would you expect to pay for it in 2010?
   
   _____¢ per lbs (Round to 1 decimal places.)

An IQ test has scores converted to Z scores. What % of people fall below a z = -2? Group of answer choices

2.28%

47.7%

97.7%

2%

How large a sample should be selected to provide a 95% confidence interval with a margin of error of 6? Assume that the population standard deviation is 40 . Round your answer to next whole number.

A student researcher compares the ages of cars owned by students and cars owned by faculty at a local state college. A sample of 217 cars owned by students had an average age of 7.62 years. A sample of 252 cars owned by faculty had an average age of 6.266.26 years. Assume that the population standard deviation for cars owned by students is 2.67 years, while the population standard deviation for cars owned by faculty is 3.41 years. Determine the 99% confidence interval for the difference between the true mean ages for cars owned by students and faculty.

Step 1 of 3 :  

Find the point estimate for the true difference between the population means.