In a city, 60% of the voters are in favor of building a new park. An interviewer intends to conduct a survey.

a. If the interviewer selects 20 people randomly, what is the probability that more than 15 of them will favor building the park?

b. Instead of choosing 20 people as in part a, suppose that the interviewer wants to conduct the survey until he has found exactly 12 who are in favor of the park. What is the probability that the first 12 people surveyed all favor the park (in which case the interviewer can stop)? What is the probability that the interviewer can stop after interviewing the thirteenth subject? What is the probability that the interviewer can stop after interviewing the eighteenth subject?

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The breaking strength of a rivet has a mean value of 10,000 psi and a standard deviation of 500 psi.
a. What is the probability that the sample mean breaking strength for a random sample of 40 rivets is between 9900 and 10,200.
b. If the sample size had been 15 rather than 40, could the probability requested in part (a) b

I need some guidance in how to calculate probabilities without knowing the std deviation.
Population = 3005
calculate P(x-bar > 50.8) for sample size of n = 253
calculate P(x-bar > 50.6) for sample size of n = 134
calculate P(x-bar > 51) for sample size of n = 119
Then combine the two probabilities 51 a

The time spent using e-mail per session is normally distributed, µ = 8 minutes and σ = 2 minutes. If you select a random sample of 25 sessions, then:
a. What is the probability that the sample mean is between 7.8 and 8.2 minutes?
b. What is the probability that the sample mean is between 7.5 and 8.2 minutes?
c. If you sel

Question 3
An experiment consists of rolling one die. Let A be event that the die shows more than one, B be event that the die shows more than 4, and C be event that die shows an even number.
a) List the sample space of this experiment.
b) Find P(A), P(B), P(C)
c) Find P(A or C), P(A or B), P(A and C), P(B and C)
d) A

In computing sample size for estimating population proportions, the formula involves p(1-p) (where we don't know p). We use p = ½ if we don't know anything about it, since that is a "worst case". Find the values of p(1-p) for p=.01, .02, .05, .10, .15, .20, .30, .40., .50, .60, .70,.80, .85, .90, .95, .98, and.99. Be prepared t

I have been struggling with theses two following problems:
illustration: age a(0.00%) b(0.01-0.9%) c(>_0.10%)
d 0-19 142 7 6 155
e 20-39 47 8 41 96
f 40-59 29 8 77

A normal population has a mean of 80.0 and a standard deviation of 14.0. Compute the probability of a value between 75.0 and 90.0. Compute the probability of a value 75.0 or less. Compute the probability of a value between 55.0 and 70.0.
In a binomial situation n = 4 and p = .25. Determine the probabilities of the following e

1. A mail order company tracks the number of returns it receives each day. Information for the last 50 days shows
Number of returns Number of days
0 - 99 6
100 - 199 20
200 - 299 15
300 or more 9
a. How many sample points are there?
b. List and

Q1: Why does the sample size play such an important role in reducing the standard error of the mean? What are the implications of increasing the sample size?
Q2: Why might one be interested in determining a sample size before a study is undertaken? How do population variability and a level of certainty affect the size of

Control A certain machine that is used to manufacture screws produces a defect rate of .01. A random sample of 20 screws is selected. Find the probabilities that the sample contains the following.
Exactly 4 defective screws
No more than 4 defective screws