Math Answers

If 10% of the television pictures tubes burn out before their guarantee period, what is the probability that out of 6 tubes 3 are burnt before guarantee expires.

A cell phone company is interested to know more about the behaviour of customers who exceed their free minutes included on their basic cell phone contracts. They evaluate such customers and find that the excess time follows an exponential distribution with a mean of 15 minutes. For a random sample of 50 customers who exceed their free minutes’ allowance, what is the probability that their average excess time is longer than 18 minutes?

A company has two manufacturing plants I and II.in a quality control inspection operation,a random sample of 50 items produced by plant I gave 8 defective while a sample of 50 from plant II gave 12 defective construct confidence interval for the difference in the proportion of items produced by the two plants..

Faced with two distinct demand functions:

Q1=24-0.2P1

Q2=10-0.05P2

Company XYZ prepares this for jam, which are labeled to have a mass of

500 grams. During the preparation the tins are set to have a mean mass of

550 grams with a standard deviation of 20 grams. One tin is selected from a

large batch containing 100 and is found to have a mass of 500 grams. Assuming the masses are normally distributed, test whether the mass of this tin is significantly different from 550 gram at 5% level of significance.

For a certain group of individuals, the av- erage heart rate is 72 beats per minute. Assume the vari- able is normally distributed and the standard deviation is 3 beats per minute. If a subject is selected at random, find the probability that the person has the following heart rate.

a. Between 68 and 74 beats per minute b. Higher than 70 beats per minute

c. Less than 75 beats per minute 

A shipment of 20 similar laptop computers to a retail outlet contains 3 that are defective. If a school makes a random purchase of 2 of these computers, find the probability distribution for the number of defectives. Show the table in your solution. Round off answers to 4 decimal places.

Solve the following set of recurrence relations and initial conditions3an-1+n^2-3,n>1,a0=1

Determine the area under the standard normal distribution curve between z=1.25 and z= -1.85

Based on the table stated in appendix a, determine the area under the standard normal distribution curve between z=0 and z= -1.15