Statistics and Probability Answers

b) At a supermarket 80% of customers pay by credit card. Find the probability that a randomly selected sample of ten customers,
(i) Exactly two pay by credit card
(ii)Less than three pay by credit card

A machine produce 15% defective components.In a sample of 5,drawn at random use the binomial distribution to find the probabilities that :
A) there'll be 4 defective items
B) there'll not be more than 3 defective items.
C) All the items will be non defective

the Wechsler iq test is designed so that the mean is 100 and the standard deviation is 15 for the population of normal adults. listed below are iq scores for professional pilots. it is claimed that because professional pilots are a more homogeneous group than the general population, they have iq with a standard deviation less than 15. test the claim using a 0.5 significance level.
121 112 115 121 116 107 127 98 116 101 130 114

assume we want to estimate the mean cost of computer repairs for the population of consumers. How many consumers randomly selected for the survey if we want to be 95% confident that the sample mean is within $2 of the population mean?
(margin of error e=2, a=0.5, o=12 and za/2 = 1.96

A study is done to determine if students in the California state university system take longer to graduate, on average,
than students enrolled in private universities. One hundred students from both the California state university system and
private universities are surveyed. Suppose that from years of research, it is known that the population standard deviations
are 1.5811 years and 1 year, respectively. The following data are collected. The California state university system students
took on average 4.5 years with a standard deviation of 0.8. The private university students took on average 4.1 years with a
standard deviation of 0.3.

The probability that A, B and C can solve a problem are 4/5, 2/3 and 3/7 respectively. The probability of problem being solved by A and B is 8/15, B and C is 2/7, A and C is 12/15. The probability of problem being solved by all three is 8/35. Find the probability that problem is not solved by anyone

The management of savings centre has calculated mean of 42 saving accounts Rs.75000 and slandered deviation Rs.10000. you have to conclude that would it be reasonable that the population mean is less than Rs.100000 by using 5% significance level.

the wechsler IQ is designed so that the means is 100 and the standard deviation is 15 for the population of normal adults. listed below are IQ scores for professional pilots. it is claimed that because professional pilots are a more homogeneous group than the general population, they have IQ scores with a standard deviation less than 15. test that claim using a .05 significance level. 121 116 115 121 116 107 127 98 116 101 130 114

In an effort to estimate the annual income for new graduates, data were collected from 100 new graduates over a 1-year period. Assume a population standard deviation of $2,000.

If the sample mean is $15,000, what is the 95% confidence interval for the population mean?

a. $14,590 to $15,410
b. $14,668 to $15,332
c. $14,608 to $15,392
d. $14,603 to $15,396
e. $14,534 to $15,466

If the sample mean is $15,000, what is the 98% confidence interval for the population mean?

a. $14,668 to $15,332
b. $14,608 to $15,392
c. $14,603 to $15,396
d. $14,534 to $15,466
e. $14,590 to $15,410

Which of the following statements is true regarding the confidence interval of a population mean?

a. The higher the confidence level required, the smaller the confidence interval reported.
b. The lower the confidence level required, the larger the confidence interval reported.
c. There is no relationship between the confidence level and the confidence interval reported.
d. The higher the confidence level required, the larger the confidence interval reported.