Statistics and Probability Answers

6. A magazine published data on the best small firms in a certain year. These were firms that had been publicly traded for at least a year, have a stock price of at least $5 per share, and have reported annual revenue between $5 million and $1 billion. The table below shows the ages of the corporate CEOs for a random sample of these firms.
48 59 50 60 56
59 74 63 53 50
59 60 60 57 46
55 63 57 47 55
57 43 61 62 49
67 67 55 55 49
Use this sample data to construct a 90% confidence interval for the mean age of CEO's for these top small firms. Use the Student's t-distribution. (Round your answers to two decimal places.)

In a recent sample of 85 used cars sales costs, the sample mean was $6,925 with a standard deviation of $3,159. Assume the underlying distribution is approximately normal.
a. what is the random x variable
b.Construct a 95% confidence interval for the population mean cost of a used car.
(i) State the confidence interval. (Round your answers to one decimal place.)
sketch the graph a/2= CL=
Calucate error bound

where the mean is 845.2 h and standard deviation of 94.2 h, what fraction of the bulbs has the capacity to function for ≤1100 hours?

A raffle is held and the grand prize is a $1000 plasma television. The tickets are sold for $1 each, if 1000 tickets were sold, find the expected value of one ticket.

Fifteen trainees in a technical program are randomly assigned to three different types of
instructional approaches, all of which are concerned with developing a specified level of skill
in computer-assisted design. The achievement test scores at the conclusion of the
instructional unit are reported in Table along with the mean performance score associated
with each instructional approach. Use the analysis of variance procedure to test the null
hypothesis that the three-sample means were obtained from the same population, using the
5 percent level of significance for the test.

A mall supervisor has found that mall sellers, on the average, complete a certain task in 10 minutes. If the times required to complete the task are approximately normally distributed with a standard deviation of 3 minutes, find: (3 marks each)
a. The proportion of mall sellers completing the task in less than 4 minutes
b. The proportion of mall sellers requiring more than 5 minutes to complete the task
c. The probability that a mall seller who has just been assigned the task will complete it within 3 minutes

In a study by Thomas et al. (A-14) the Poisson distribution was used to model the number of patients per month referred to an oncologist. The researchers use a rate of 15.8 patients per month that are referred to the oncologist. Use PHStat and a rate of 16 patients per month to calculate the probability that in a month

Suppose that scores on a national entrance exam are normally distributed with mean 1000 and standard deviation 100.Which of the following is false?

A new internet provider claims their system you can get transmission speed of 400 kilobits per second. Specify both statically and in English, the null and alternative hypotheses a potential customer should investigate if she is worried that the connection is really slower than advertised.explain your reasoning