Math Answers

Find the probability of z lying between z=0 and z=2.3.

How many bijections (bijective functions) are there from A to A with the

property that no element of A is mapped to itself? (A is a set with 5 elements)

A cylindrical jug that carries 5 ℓ of water when it is filled to the brim, has a height of 20 cm

What is the probability that a hired bike will be deemed beyond repair provided that the wheels get damaged independently of each other

Thabi and Senzo are marking 180 scripts for grade 12.

Thabi took 3 minutes to finish 1 paper.

Senzo took 1,5 minutes to finish 1 paper.

How long will it take them to finish 180 scripts?

Assume the service life is distributed normally, a random sample of several electronic stuff with a service life (years): 6, 7, 7, 7, 6, 8, 8, 7, 6.

Does this indicate that the average lifespan of a shaker from Onix is not the same as 7

year? Do hypothesis testing with a significance level:

a. 1%

b. 5%

c. 10%

The heights of 2-year-old children are normally distributed with a mean of 32 inches and a standard deviation of 1.5 inches. Pediatricians regularly measure the heights of toddlers to determine whether there is a problem. There may be a problem when a child is in the top or bottom 5% of heights. Determine the heights of 2-year-old children that could be a problem.

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

_______3. If a sample of 10 cups of ice cream is selected, what is the probability that the mean

of the sample will be larger than 670 mg?

A.   11.84%                       B. 14.18%            C. 18.41%           D. 19.41%

_______4. If a sample of 10 cups of ice cream is selected, what is the probability that the mean

of the sample will be smaller than 625 mg?

A.   0.0008%                     B. 0.008%            C. 0.08%             D. 0.8%

_______5. If a sample of 10 cups of ice cream is selected, what is the probability that the mean

of the sample will be larger than 637 mg?

A.   91.28%                       B. 98.12%            C. 98.21%           D. 99.21%

A jar contains 9 red marbles numbered 1 to 9 and 3 blue marbles numbered 1 to 3. A marble is drawn at random from the jar. Find the probability that the marble is red or even-numbered?

 A sample of 100 recorded deaths in the United States during the past year showed an average life span of 71.8 years. Assuming a population standard deviation of 8.9 years,

does this seem to indicate that the average life span today is greater than 70 years? Use a level of significance:

a. 1%

b. 5%

c. 10%