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Question 313922: A statistician is considering using a 99% confidence interval for a study instead of a 95% confidence interval. What happens to the required sample size if the confidence level is increased from 95% to 99% and the same error is required in each case?
Click here to see answer by stanbon(57967)

Question 313918: The ages of 25 employees in a company are listed below in a stem and leaf plot. What is the probability that a worker chosen at random will have an age greater than or equal to 30 and less than or equal to 39?

Click here to see answer by stanbon(57967)

Question 314085: The heights of a certain species of plant are normally distributed, with mean 22 cm and standard deviation 3 cm. What is the probability that a plant chosen at random will be between 19.75 and 24.25 cm tall?
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Question 314172: The probability that an open heart operation is successful is 0.84. what is the probability that in two random selected open heart operations, at least one will be successful?
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Question 314211: a magazine article cited the numbers on household income in Berea, KY was given by the U.S. Census Bureau. Was a sample or the population used?
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Question 314246: The mean household incomes of randomly selected residents of Temecula City, CA in U.S. dollars are listed.
$62,050 $59,250 $65,100 $66,000 $32,000
$69,150 $32,000 $61,120 $61,000

From this data set, find the sample mean, median, mode and range for the household incomes. Round each to the nearest dollar if necessary. Include units with each answer.
Which of the numbers you calculated is a better measure of the central tendency of the incomes given? Give a specific statistical reason for your conclusion.
Click here to see answer by Jstrasner(106)

Question 314281: There are 5 women and 7 men who are reporters for a magazine. There are 6 articles that need to be written. If 6 reporters are chosen at random to write the articles, what is the probability that 3 are men and 3 are women?
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Question 314346: A card is selected from a deck of 52 playing cards. Find the probability of selecting
1. a prime number under 10 given the card is a heart
2. a spade or a club given the card is black
3. a queen, given the card is not a spade.
Here's how I did number 1:
13 cards are hearts but only 4 of them are prime (2, 3, 5,7)
so, 4/13.
Please help with number 2 and 3. Thank you so much.
Click here to see answer by stanbon(57967)

Question 314338: A survey showed that 23% of college students read newspapers on a regular basis and that 83% of college students regularly watch the news on TV. The survey also showed that 21% of college students both follow TV news regularly and read newspapers regularly.
(a) What is the probability that a student watches TV news regularly, given that he or she regularly reads newspapers? Round your answer to 2 decimal places.
(b) What is the probability that a randomly selected college student reads newspapers regularly, given that he or she watches TV news regularly? Round your answer to 2 decimal places.

Click here to see answer by stanbon(57967)

Question 314401: Statistics-Hypotheses Testing
Describe the type of test statistic you would use and state the Null and Alternate Hypotheses.
a. Beef patties for McDonalds are prepared and packaged at a processing plant and shipped frozen to the individual outlets. From past experience, it is known that the weight of individual patties is normally distributed with a mean () of 4 oz and a standard deviation( ) of .5 oz.. If a random sample of 25 patties has an average weight of 4.235 oz., should management feel the patties are not meeting weight specifications?
Type of test statistic_______________
Hypotheses: H0 _______________________
H1 _______________________

b. Suppose that an automobile manufacturer designed a radically new lightweight engine and wants to recommend the grade of gasoline to use. The four grades are regular, regular leaded, premium and super premium. The test car made 30 trial runs on the test track using each of the four grades. What test would they use to base their recommendation?
Type of test statistic_________________
Hypotheses: H0 _______________________
H1 _______________________

c. A random sample of current students at United University yields the following data:
Major Male Female
Business 20 10
Engineering 15 5
Liberal Arts 30 20
Science 30 20
Use the data to determine if major is independent of sex.
Type of test statistic: _________________
Hypotheses: H0 _______________________
H1 _______________________

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Question 314396: # 1.) The weight of full boxes of frosted Mini-wheat cereal are normally distributed with a standard deviation of 0.52 oz. A sample of 18 randomly selected boxes produced a mean weight of 24.3 oz. Find the 95% confidence interval for the true mean weight of a box of this cereal.
# 2.) We are interested in estimating the mean life of a new product. How large a sample do we need to take in order to estimate the mean to within 0.20 of a standard deviation with 90% confidence?
Click here to see answer by stanbon(57967)

Question 314394: Hello I have quite a lenghty problem. I think I figured it right but I am not sure. I appreciate all the help.
Vehicle speeds at a certain highway location are believed to have approx. a normal distribution with mean=60 mph and standard deviation=6 mph.
Speeds for random sample n=36. Determine the values in the sentence: For samples n=36 there is a 95% chance the vehicle will be between __ and ___.
I have figured it this way 60-2(6)=48 and 60+2(6)=72.
I also figured the standard error to be: 6/sqrt 36=6/6=1
I hoping I'm right because then I know what I am doing.
Thanks,
Donnie
Click here to see answer by rapaljer(4667)

Question 314484: The letters of the word Mississippi are placed in a hat. What is the probability that the first two letters drawn are both i if the first letter drawn is not replaced?

Click here to see answer by Edwin McCravy(8999)

Question 314475: According to the U. S. Census Bureau, the total 2008 U.S. population was 303,824,640. The chart below summarizes the 2008 population for five U.S. States.
U. S. State
2008 Population

Alaska
686,293

California
36,756,666

Hawaii
1,288,198

Idaho
1,523,816

Indiana
6,376,792

SOURCE: U. S. Census Bureau

What is the probability that a randomly selected U.S. resident did not live in Alaska? Show step by step work. Round solution to the nearest thousandth
Click here to see answer by Fombitz(13828)

Question 314474: A computer equipment manufacturing company tested the reliability of a CPU.
It measured the time to failure of 13 randomly sampled CPUs it produced. Listed below are the 13 measurements (in months) for the time to first failure.
21 32 37 29 37 42 28 26 28 37
31 24 27

From this data, find the sample mean, median, mode and midrange for this data. Round each to the nearest tenth, if needed. Include units with each answer.

Click here to see answer by Fombitz(13828)

Question 314573: a bag contains eight green marbles, five white marbles and two red marbles. what is the probability of drawing a red marble from the bag ?
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Question 314590: a spinner has the number 1 through 9. the spinner spin once. what is the probability of p(3,6or8)in precent
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Question 314592: a spinner has the number 1 through 9 what is the probability of(less than 6) in decimal.
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Question 314593: a six-sided cube is rolled. find the probability of (4).
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Question 314597: When rolling a cube,what is the probability of rolling a number greater than 6
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Question 314595: a six-sided cub is rolled. find the probability of (6)
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Question 314604: If you flip two coins, the probability that both will come up heads is _____.
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Question 314444: 2. Assume the body temperatures of healthy adults are normally distributed with a mean of 98.20 °F and a standard deviation of 0.62 °F (based on data from the University of Maryland researchers).
a. If you have a body temperature of 99.00 °F, what is your percentile score?
b. Convert 99.00 °F to a standard score (or a z-score).
c. Is a body temperature of 99.00 °F unusual? Why or why not?
d. Fifty adults are randomly selected. What is the likelihood that the mean of their body temperatures is 97.98 °F or lower?
e. A person’s body temperature is found to be 101.00 °F. Is the result unusual? Why or why not? What should you conclude?
f. What body temperature is the 95th percentile?
g. What body temperature is the 5th percentile?
h. Bellevue Hospital in New York City uses 100.6 °F as the lowest temperature considered to indicate a fever. What percentage of normal and healthy adults would be considered to have a fever? Does this percentage suggest that a cutoff of 100.6 °F is appropriate?

Click here to see answer by Fombitz(13828)

Question 314623: please choose one.
Probability can be calculated at maximum vale ?
100%
150%
180%
360%
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Question 314681: During a space mission, the primary computer system is backed up by two secondary systems. They operate independently of one another, and there is a 90% probability that a computer system will survive the mission. What is the probability that:
All three systems will survive the mission?
At least one system will survive the mission?
Click here to see answer by stanbon(57967)

Question 314741: I have been working on my homework all day and this may be the simplest of problems but I am confusing myself and I was wondering if I could get a little help figuring it out. Can you show me how you get the answer.
Suppose on a highway with a speed limit of 65 mph, the speed of cars are independent and normally distributed with an average speed = 65 mph and standard deviation = 5 mph. What is the expected value of the sample mean speed in a random sample of n = 100 cars?
A) 13 mph
B) 0.65 mph
C) 6.5 mph
D) 65 mph
Thanks,
Dave

Click here to see answer by stanbon(57967)

Question 314594: As a part of contract negotiations, management claims that the mean annual salary for clerical workers is $30,000. The union would like to show the mean is lower. A random sample of 17 annual clerical salaries is collected and yields a sample mean of $28,157 and standard deviation of $3500. Is this sufficient evidence to support the Union's position? Use a significance level of a = 0.05. You may assume the mean annual salaries are normally distributed.
Click here to see answer by stanbon(57967)

Question 314759: After studying all night for a final exam, a bleary-eyed student randomly grabs 2 socks from a drawer containing 9 black, 6 brown and 2 blue socks, all mixed together. What is the probability that she grabs a matched pair?

Click here to see answer by Edwin McCravy(8999)

Question 314788: Suppose that the weight of apples eaten by individual Americans can be described by a normal probability distribution with mean μ = 15 pounds and standard deviation σ = 5 pounds per < year.
For a random sample of n = 16 people, what is the standard deviation of the sampling distribution of the sample mean ̄x?
For a random sample of n = 16 people, what is the mean of the sampling distribution of the sample mean ̄x?
For a random sample of n = 16 people, what is the z-score for a sample mean ̄x = 10 pounds?
For a random sample of n = 9 people, what is the z-score for a sample mean ̄x = 18 pounds?

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Question 314737:
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Question 314879: is it possible for the probability of an event to be 8.12 *10^-9
Click here to see answer by rapaljer(4667)

Question 314896: Given regular die (6 sides),(a) how many possible outcomes are there? (b)List the possible outcomes (Assuming this is a fair die (all have the same probability), what is the probability), what is teh possibility of tossing a 5?
Click here to see answer by solver91311(17077)

Question 314906: The ages of 25 employees in a company are listed below in a stem and leaf plot. What is the probability that a worker chosen at random will have an age greater than or equal to 30 and less than or equal to 39?
Click here to see answer by solver91311(17077)

Question 314907:
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Question 314848: A bag contains some balls of which 1/4 are red. forty more balls of which 5 are red are added. if 1/5 of all the balls are red, how many balls were there originally?
Click here to see answer by Fombitz(13828)

Question 314863: Assume that adults have IQ scored that are normally distributed with a mean of 100 and a standard deviation of 15. Find the probabilty that a randomly selveted adult has an IQ between 81 and 119? I can't find thee formula on how to find the answer.
Click here to see answer by Fombitz(13828)

Question 314851: Three cards are drawn in succession from a deck without replacement. find the probaility distribution for the number of spades.
Click here to see answer by Fombitz(13828)

Question 315056: what does nCr stand for? email me at shylasolis@yahoo.com
Click here to see answer by rapaljer(4667)

Question 315032: An economics club has 30 members.
a) If a committee of 4 is to be selected, in how many ways can the selection be made?
b) In how many ways can a committee of at least 1 and at most 3 be selected?
Click here to see answer by stanbon(57967)

Question 315061: In how many ways can 6 shuttle vans line up at the airport?
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Question 315063: PLEASE HELP ME SOLVE THIS PROBLEM

2.Use the method specified to perform the hypothesis test for the population
mean . WeatherBug say that the mean daily high for December in a large Florida city is F. WFLA weather suspects that this temperature is not accurate. A hypothesis test is performed to determine if the mean is actually lower than F. Assume that the population standard deviation of  = F. A sample of mean daily temperatures for December over the past 40 years gives F. At  = 0.01, does the data provide sufficient evidence to conclude that the mean temperature is lower than F.

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Question 315031: What is the expected value for the random variable:
y 4 6 8 10
--------------------------------
P(y) .4 .4 .05 .15
Click here to see answer by Fombitz(13828)

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