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Question 21775: In a shooting game the probabilities that kent and fred will hit a target are 2/3 and 3/4 respectively. What is the probability that the target is hit when both shoot at it?

In a shooting game the probabilities that kent and fred and mike will hit a target are 2/3 and 3/4 and 1/5 respectively. What is the probability that the target is hit when both shoot at it?

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Question 21655: Please Please PLease help me with this!
The operations manager at a light bulb factory wants to determine whether there is any difference in the mean life expectancy of bulbs manufactured on two different types of machines. The population standard deviation of machine I is 110 hours and of machine II is 125 hours. A random sample of 24 light bulbs from machine I indicates a sample mean of 375 hours and a similar sample of 25 bulbs from machine II indicates a sample mean of 362 hours.
a) Using a 0.05 level of significance, is there any evidence of a difference in the mean life of bulbs produced by the two types of machines?

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Question 21549: Please, please help!
After you complete this exam, you and two friends decide to go to McDonald’s to celebrate. Last month McDonald’s filled 90% of the orders accurately. What is the probability that:
a) All three orders will be filled accurately?
b) None of the three orders will be filled accurately?
c) At least 2 of the 3 orders will be filled accurately?

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Question 65018: Could you help me please with this problem below:
The number of eggs of a female house fly lays during her lifetime is normally distributed, with a mean of 800 eggs and a standard deviation of 100 eggs. Random sample of size 15 are drawn from this population and the mean of each sample is determined.
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Question 65025: Help I'm lost. PLEASE!
An annuity has a record of 9.58% annual growth compounded annually. How long will it take to double your money in this fund
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Question 65113: Hi I'm not a card player and I am having trouble. Please help. A single card is chosen at random from a standard 52-card deck. Find the odds against its being a 1.heart, 2.a red queen, 3. a king or a black face card.
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Question 65226: Hi all see this 2 Questions plz
1- A die was rolled 720 times , what is the probability that the number 4 will be exactly 125 times ?
2- What is the probability of getting at most three heads in 8 flips of balanced coin ?

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Question 65256: A game involving rolling a pair of 2 dice 24 times. The game is won if at least one double 6 occurs. What is the probably of winning this game?
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Question 65254: Suppose a pond has only three types of fish: catfish, trout and bass, in the ration 5:3:3. There are 50 fish in total. Assuming you are allowed to only catch three fish before throwing them back, find the probability of catching three trout, or catching the three types of fish in alphabetical order.\

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Question 65255: Suppose there are 6 prizes hidden in the boxes of a particular cereal brand. How many boxes of the cereal would you expect to buy before collected all 6 prizes?
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Question 65387: there are 35 machine parts and 8 are defective. what is the probability that you randomly select 5 parts that one will be defective?
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Question 65372: HI, i need help with this problem:
A new shipment of 9 VCRs, which will be offered at a very low price, are delivered to a store. Unknow to the manager, 4 of the VCRs are defective.
Determine the probability that at least one of the first 3 VCRs sold is defective. Express your answer to the nearest tenth of one percent.
Click here to see answer by stanbon(57953)

Question 65418: When driving and automobile to work you would think that half the turns would be right hand turns. When conducting a hypothesis test, out of 25 total turns on my route to work I found that 13 were right hand turns. using probability=.10 determine if the true proportion of right hand turns is actually equal to (.50) Are there legitimate factors which would make a driver have a larger or smaller proportion of right-hand turns?
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Question 65432: HI, i need help with this problem:
A new shipment of 9 VCRs, which will be offered at a very low price, are delivered to a store. Unknow to the manager, 4 of the VCRs are defective.
Determine the probability that at least one of the first 3 VCRs sold is defective. Express your answer to the nearest tenth of one percent.:
Click here to see answer by Edwin McCravy(8999)

Question 65252: Two friends who have unpredictable lunch hours agree to meet for lunch at their favourite restaurant whenever possible. Neither wishes o eat alone and each dislikes waiting for the other, so they agree that each will arrive at a random time between noon and 1pm, and each will wait for the other for 15 minutes or until 1:00. What is the probably that the friends will meet for lunch on a given day?
Click here to see answer by venugopalramana(3286)

Question 65917: When I conducted a test I found that a paragraph containing 566 words, 51 of them were the letter e. Test claim that 12.7% of all letters in the english text are e. Test the claim that the letter e appears 12.7% of the time. Use probability = 0.01.
Click here to see answer by stanbon(57953)

Question 66342: Frederique, who arrives home at 6:42 p.m., is home to receive a call that can come at any time between 6:40 and 6:50.
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Question 66426: A spinner is divided into 8 congruent regions numbered 1 through 8. The spinner is spun once.Find the probability of each event.
1. The number is even or divisible by 3.
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Question 16723: for a situation of the mean of scores to be 500 and the standard deviation to be 100 and a survey of 16...I am trying to find out how to get the expected value of the average of scores (mean of the sampling distribution) .. My main question isn't WHAT the answer is, but how I go about finding it.
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Question 66657: Business and finance. The revenue for a sandwich shop is directly proportional
to its advertising budget. When the owner spent $2000 a month on advertising, the
revenue was $120,000. If the revenue is now $180,000, how much is the owner
spending on advertising?
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Question 66785: Julius learned about different types of angles in class today.He was asked to find the complement of an angle which measures 40 degrees as part of his homework.What is the complement of an angle which measures 40 degrees?
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Question 66784: Simon is rolling a fair number cube and flipping a coin.What is the probability that he will roll the number 3 and the coin will land on heads?
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Question 66782: Ms.Thomson's class consists of 12 girls and 13 boys. They all put their names in a hat and the teahcer was going to randomly choose two different students to be assistant teachers for the week. What is the probability that it will be a boy and a girl?
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Question 16285: Suppose you have a dark closet containing 7 blue shirts, 5 yellow shirts and 8 white shirts. You pick 2 shirts from the closet. Find each probability.
A. P(blue then yellow) with replacing
B. P (blue then yellow) without replacing
C. P (yellow then yellow) with replacing
D. P (yellow then yellow) without replacing
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Question 66832: how do you add and subtract radicals?
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Question 66834: i just started algebra 2. we are just starting to go over radicals. is there anyone who can help me understand how to add and subtract them? I just started it, so its not complex yet, its just the "easy stuff" or so thats what everyone says.
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Question 67172: A fair coin tossed 12 times. What is the porbability that the coin will land heads up on the ninth toss?
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Question 67169: two cards are randomly selected from a standard-52 card deck. What is the probability of getting 2 hearts or 2 numbers les than 4 (count aces as one)
thankyou
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Question 15710: The letters a, b, c, and d will be used to form passwords for the schools computer system. How many 4 letter passwords maybe formed if the letters can be used more than once in any passwrd?

Click here to see answer by cassiroberts(11)

Question 67265: 1. The average yearly cost per household of owning a dog is $186.80. Suppose that we randomly select 50 households that own a dog. What is the probability that the sample mean for these 50 households is less than $175.00.
Assume o = $32
z =X - u/o
z = 175.00- 186.80/32 = -11.8/32 = -3.6875
0.5000-0.1406 = 0.6406
P(X < 175) = 0.6406 = 64% (not sure if used correct steps)
b. Sample Mean - mean/ standard deviation/ square root of N.
175 - 186.80 / 32/(squqare root of 50 = -2.607
0.5000 +4955 = .9955 = 99% or 100%

2. The average teacher’s salary in North Dakota is $29863. Assume a normal distribution with  = $5100.
a. What is the probability that a randomly selected teacher’s salary is greater than $40,000?
b. What is the probability that the mean for a sample of 80 teachers’ salaries is greater than $30,000
a.
z = 29863 - 40000/5100 = -10137/5100 = -1.98 0.5000+.4761 = .9761 = 98%
P(X>40,000)

3. For a certain year the average annual salary in Pennsylvania was $24,393. Assume that salaries were normally distributed for a certain group of wage earners, and the standard deviation of this group was $4362.
a. Find the probability that randomly selected individual earned less than $26,000.
b. Find the probability that, for a randomly selected sample of 25 individuals, the mean salary was less than $26,000.
c. Why is the probability for Part b higher than the probability for Part a?

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Question 67802: I am having trouble with calculating p-values. I have two problems that I just can't figure out. This is the first:
A survey of 120 high school students shows that 39 of them work over 20 hours per week during the school year. Does it demonstrate the conjecture that more than 25% of the high school students work over 20 hours per week during the school year? (Answer by calculating the P-value.)
I started out calculating the sample proportion:
p^ = x / n = 39/120 = 0.325
which means that 32.5 % work more than 20 hrs. per week, which is more than 25%, but how do you show that by calculating the P-value? I tried to figure out the test statistic, but got lost. Thanks for any help you can give.

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Question 67808: I am completely lost trying to understand population proportion and p-values. I understand the concepts, just not how to work with them. This is the second of 2 questions that I am submitting.
Each year, an insurance company reviews its claim experience in order to set future rates. Regarding their damage-only automobile policies, at least one claim was made on 2073 of the 12,299 policies in effect for the year. Treat these data as a random sample for the population of all possible damage-only policies that could be issued.
a)Test, at level α = .05, the null hypothesis that the probability of at least one claim is 0.16 versus a two-sided alternative.
b)Calculate the P-value and comment on the strength of evidence.
This is what I did so far:
p^ = 2073/12,299 = 0.1686
Ho: p > 0.16
H1: p < 0.16
This doesn't make sense to me, but if I made Ho: p = 0.16 and H1: p ≠ 0.16, wouldn't I have a two-sided alternative?
Z= 0.1686 - 0.16 / √(0.16)(0.84)/12,299 = 2.61
Z.05 = 1.645

If any of this is right, please let me know, and thanks for any help in completing the problem that you can give.

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Question 67888: A circular pool of radius 12ft is enclosed within a rectangular yard measuring 50ft by 100ft. If a ball from an adjacent golf course lands at a random point within the yard, what is the probability that the ball lands in the pool?
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Question 67886: The question is asking this: A wallet contains 4 bills with denominations of $1,$5,$10, and $20. You choose 2 of the 4 bills from the wallet at random and add the dollar amounts. What is the sample space? How many outcomes are there? What is the probability of getting $15? What is the probability of getting $50? What is the probability of getting at least $25??
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Question 68168: A tree diagram shows the possibilites for boys and girls in a two-child family. If a family has 2 children, what are the chances that one child is a girl and one child is a boy?
A 1/4
B 1/3
C 1/2
D 3/4
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Question 68169: A number cube labeled 1-6 is rolled and a spinner numbered A-D is spun. What is the probability of James getting a 1 and an A?
A 1/24
B 1/10
C 1/6
D 1/4
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Question 68170: Becky has a box of markers that contains 1 blue, 4 black, 2 red, and 3 green markers. Becky picks one marker from the box, replaces it, and pickes another marker. What is the probability that she will pick 2 red markers?
A 1/25
B 1/10
C 1/5
D 1/2
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Question 68840: Are each of the outcomes as likely to occur as any of the others?
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Question 68843: A jar contains 5 green marbles and 3 orange marbles. You randomly choose a marble from the jar. After replacing the marble, you choose a second marble. What is the probability that both marbles are orange?
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Question 68848: 3/8A jar contains 5 green marbles and 3 orange marbles. You randomly choose a marble from the jar. After replacing the marble, you choose a second marble. What is the probability that thr first marble is green and the second marble is orange?
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Question 68858: A jar contains 5 green marbles and 3 orange marbles. You randomly choose a marble from the jar. Wothout replacing the marble, you choose a second marble. What is the probability that the first marble is green and the second is orange?
Click here to see answer by jim_thompson5910(28699)

Question 68857: A jar contains 5 green marbles and 3 orange marbles. you randomly choose a marble from a jar. Without replacing the marble, you choose a second marble. What is the probability that both marbles are orange?
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Question 68850: You roll two dice. What is the probability the sum of the first is 5 and the sum on the second roll is 8?
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