Statistics and Probability Answers

The average length of time for students to enroll in college is 6 hours and 10 minutes. Computerized enrolment is being tested. In a random sample of 180 students, it was found out that the average time for them to enroll is 2 hours and 45 minutes with a standard deviation of 20 minutes. At = 0.01, does this indicate that the average time for students to enroll using computerized enrolment is less than the regular enrolment?

A new drug on the market is claimed by its manufacturers to reduce overweight women by 4.55 kg per month with standard deviation of 0.91 kg. Ten women chosen at random have reported losing an average of 4.05 kg within a month. Does this data support the claim of the manufacturer at 0.05 level of significance?

A new drug on the market is claimed by its manufacturers to reduce overweight women by 4.55 kg per month with standard deviation of 0.91 kg. Ten women chosen at random have reported losing an average of 4.05 kg within a month. Does this data support the claim of the manufacturer at 0.05 level of significance?

The mean number of births per minute in a country in a recent year was about nine. Find the probability that the

number of births in any given minute is (a) exactly six, (b) at least six, and (c) more than six.

The average number of miligrams (mg) of cholesterol in a cup of a certain brand of ice cream is 660 mg, the standard deviation is 35 mg. Assume the variable is normally distributed.

A. If a cup of ice cream is selected, what is the probability that the cholesterol content will be more than 670 mg?

B. If a sample of 10 cups of ice cream is selected, what is the probability that the mean of the sample will be larger that 670 mg?

For the most recent year available, the mean annual cost to attend a private university in the United States was $26,889. Assume the distribution of annual cost follows the normal distribution and the standard deviation $4,500. 95% of all students at private university pay less than what amount?

1. A population consists of six values (6, 9, 12, 15, 18, and 21). (35 points) a. Select a random sample of size 3. Explain the random sampling that you used. (3 pts.) b. How many possible samples can be drawn? (3 pls.)

c. list all possible samples and compute the mean of each sample. (10 pls.)

d. Construct a frequency distribution of the sample means obtained in step 2 including

f: P(x): P(): *P(): EP(x): Ex-P(F) and 2 P(F). (13 pts.)

e. Determine the mean, voriance and standard deviation of the sample mean. (6 pts.)

Construct the Tabular Representation and Histogram Representation of the following probability distribution:

1. In a class of 100 students, 80 students passed in all subjects, 10 failed in one subject, 7 failed in two subjects and 3 failed in three subjects. Find the probability distribution of the variable for number of subjects a student from the given class has failed in.

2. The probability of landing on 1 is 0.25. The probability of landing on 2 is 0.75. Let X be the sum of the two spins. Construct a probability distribution for the random variable x.

For a certain type of fluorescent light in a large building, the cost per bulb of replacing bulbs all at once is much less than if they are replaced individually as they burn out. It is known that the lifetime of these bulbs is normally distributed, and that 60% last longer than 2500 hours, while 30% last longer than 3000 hours.

a) What are the approximate mean and standard deviation of the lifetimes of the bulbs?

If the light bulbs are completely replaced when more than 20% have burned out, what is the time between complete replacements

Say 40% of the class is female. What is the probability that 6 of the first 10 students walking in will be female?