Tutors Answer Your Questions about Probability-and-statistics (FREE)
Question 155365: So we have a normal distribution of test scores. Mean score is 120; std deviation is 20.
What is the z-value of a test score of 160??
What is the probability of selecting a test score from the group.... a test score between 120 and 160??
Click here to see answer by stanbon(26259)   |
Question 155436: The probability is 1 in 4,000,000 that a single auto trip in the United States will result in a fatality. Over a lifetime, an average U.S. driver takes 50,000 trips.
(a) What is the probability of a fatal accident over a lifetime? Explain your reasoning carefully. Hint: Assume independent events. Why might the assumption of independence be violated?
(b) Why might a driver be tempted not to use a seat belt “just on this trip”?
Click here to see answer by stanbon(26259) |
Question 155304: At the start of the 1999 NCAA men’s basketball tournament, 64 teams were invited to compete for the national championship. Below is the number of victories that a sample of 26 of these teams had obtained during the regular season:
32,12,28,22,20,25,22,20,22,22,19,19,26
19,21,23,27,21,21,22,23,27,22,24,26,23
What is the sample median number of regular season victories?
a. 20
b. 21
c. 22
d. 23
Click here to see answer by stanbon(26259) |
Question 155303: . At the start of the 1999 NCAA men’s basketball tournament, 64 teams were invited to compete for the national championship. Below is the number of victories that a sample of 26 of these teams had obtained during the regular season:
32,12,28,22,20,25,22,20,22,22,19,19,26
19,21,23,27,21,21,22,23,27,22,24,26,23
What is the sample mean number of regular season victories?
a. 9.0
b. 12.1
c. 22.6
d. 23.6
Click here to see answer by stanbon(26259) |
Question 155216: A study of Hub Furniture regarding the payment of invoices reveals the time from billing until payment is received follows the normal distribution. The mean time until payment is received is 20 days and the standard deviation is 5 days.
a. What percent of the invoices are paid within 15 days of receipt?
b. What percent of the invoices are paid in more than 28 days?
c. What percent of the invoices are paid in more than 15 days but less than 28 days?
d. The management of Hub Furniture wants to encourage their customers to pay their monthly invoices as soon as possible. Therefore, it announced that a 2 percent reduction in price would be in effect for customers who pay within 7 days of the receipt of the invoice. What percent of customers will earn this discount?
Click here to see answer by stanbon(26259) |
Question 155575: In Indianapolis, the distance between the conference center and the airport is ten miles, and the distance between the conference center and my hotel is also ten miles.What is the probability that the hotel is closer to theairport than to the conferance center? Please Show all work.
Click here to see answer by ilana(236) |
Question 155820: John is an avid fisherman and wants to know if there is a correlation between the amount of time he spends fishing and the amount of fish he catches. He decided to keep track of the time he spent at the lake and the amount of fish he caught. The results were as follows:
Week........... 1 2 3 4 5 6
Hours at lake...2 3 2 1 4 5
Fish caught.....5 5 4 3 6 9
Use the information regarding John’s fishing trips to perform a simple (bivariate) regression analysis. Use the hours spent as the X variable, and the number of fish caught as the Y variable. Calculate r and r2, standard error of the estimate, and a confidence interval for the data. Interpret the results.
Click here to see answer by stanbon(26259) |
Question 157792: Using a square, rectangle, circle and triangle write all dimension (length, radius, etc. including units like in. ft. etc. Also use formulas.
How in the world do you do this. I'm a mom and my son has this problem in school and i have no clue. He is in 9th grade. Can anyone please help me????
Click here to see answer by Alan3354(6059)  |
Question 158167This question is from textbook
: The question is: Construct a set of twelve numbers with a mean of 7, a median of 6, and a mode of 8. I do not know how to begin, and it was not explained in class. Thank you for your help! This question is from textbook
Click here to see answer by jim_thompson5910(13787) |
Question 159170: I'm embarassed to admit that I was stumped by this question. I had "20" as my answer and was told it was incorrect. Can you explain why? Thank you.
A hotel has 50 people checking in. Of the 50, there are 16 traders; 10 MBA graduates; 10 American; and 14 women. Approximately how many of the next 50 people checking into the hotel will have MBAs?
Click here to see answer by checkley77(7035) |
Question 159146: Use the survey results below for Exercise 9 below.
This is the survey results:
39% have a pet now and have had a pet.
61% do not have a pet now.
86% have had a pet.
14% do not have a pet now and have
never had a pet.
The question is:
Find the probability that a respondent has a pet, given that the respondent has had a pet.
Click here to see answer by edjones(3292)  |
Question 159205This question is from textbook Elementary Statistics
: 4.5 ( 2, 16, 32)
2. How many ways can a basebal manager arrange a batting order of 9 player?
I did 9!= 362,880 please let me know if this is correct.
16. An inspector must select 3 tests to perform in a certain order on a manufactured part. He has a choice of 7 tests. How many ways can he perform 3 different tests?
I did 7P3 = 7!/(7-3)! = 7!/4! = 210 Please let me know if this is correct.
32. If a person can select 3 presents from 10 presents under a christmas tree, how many different combinations are there?
I did 10C3 = 10!/(10-3)!3!= 10!/7!3!= 10*9*8*7!/7!*3*2*1= 10*3*4=120
Please let me know if this is correct.
Section 4-6 problem number 6
6. A package contains 12 resistors, 3 of which are defective. If 4 are selected, fin the probability of getting
a. No defective resistors
b. 1 Defective resistor
c. 3 Defective resistors
for a. P(no defectives)= 9C4/12C4=126/495 and then I got confused.
for b P(1 defective) = 1- P(no defectives)
= 1- 9C4/12C4
= 1- 126/595
Then I get confuse becaue I'm not sure how to
subtract from the one.
for c. P(3 defective) = 3C3*9C3/12C4 = 94/495 I think i'm supposed to reduce it
but im not sure how or if this is correc.
This question is from textbook Elementary Statistics
Click here to see answer by oscargut(682)  |
Question 159164: Which of these variables are discrete and which are continuous random variables?
a. The number of new accounts established by a salesperson in a year.
b. The time between customer arrivals to a bank ATM.
c. The number of customers in Big Nick’s barber shop.
d. The amount of fuel in your car’s gas tank.
e. The number of minorities on a jury.
f. The outside temperature today.
Click here to see answer by oscargut(682) |
Question 159327: Suppose you roll a die 3 times. What is the probability that the face 6 will show up at least once?
Suppose we roll a die 2 times. How many outcomes can happen that an even-number face will not show up?
What is the probability that an even number will not show up during the two rolls?
What is the probability that an even number will show up at least once during the two rolls?
Click here to see answer by edjones(3292) |
Question 159471: This is a homework question. I do not understand about regression lines.
The question is: Find the equation of the regression line:
x 12 14 10 9 15 8
____________________________________
y 29 35 28 23 36 18
Multiple choice answer:
y = -1.2 + 2.4x
y = 1.2 + 2.4x
y = 2.4 + 1.2x
y = -2.4 + 1.2x
Which is the correct answer?
Click here to see answer by Fombitz(2113)  |
Question 159742: The directions say,"In exercise 2, consider a 10-question true/false test." The question is, 'How many ways are there to score exactly 80%? That is, how many ways are there to get exactly 2 questions wrong? Explain why choosing which questions you will get wrong determines all your answers.'
Click here to see answer by stanbon(26259) |
Question 159757This question is from textbook
: A bag contains 6 red marbles, 9 blue marbles, and 5 green marbles. You withdraw one marble, replace it, and then withdraw another marble. What is the probability that you do NOT pick two green marble?This question is from textbook
Click here to see answer by edjones(3292) |
Question 159985: 40% of students find a job in there chosen field, in a group of 5 what is the probability that at least 1 find a job in his or her field. I'm trying but my answers are way off. I don't know what i'm doing wrong.
Click here to see answer by scott8148(3382)  |
Question 160128: Find the sample proportions and test statistic for equal proportions. Is the decision close? Find the p-value.
a. Dissatisfied workers in two companies: x1 = 40, n1 = 100, x2 = 30, n2 = 100, α = .05, two tailed test.
b. Rooms rented at least a week in advance at two hotels: x1 = 24, n1 = 200, x2 = 12, n2 = 50, α = .01, left-tailed test.
c. Home equity loan default rates in two banks: x1 = 36, n1 = 480, x2 = 26, n2 = 520, α = .05, right-tailed test.
Click here to see answer by Edwin McCravy(2920) |
Question 160595: Please help! Homework question.
A person must score in the upper 2% of the population on an IQ test to qualify for membership in Mensa, the international high-IQ society. If IQ scores are normally distributed with a mean of 100 and a standard deviation of 15, what score must a person have to qualify for Mensa?
Click here to see answer by nabla(412) |
Question 160595: Please help! Homework question.
A person must score in the upper 2% of the population on an IQ test to qualify for membership in Mensa, the international high-IQ society. If IQ scores are normally distributed with a mean of 100 and a standard deviation of 15, what score must a person have to qualify for Mensa?
Click here to see answer by MathLover1(1183)  |
Question 160722This question is from textbook
: 11.24 In a bumper test, three types of autos were deliberately crashed into a barrier at 5 mph, and the
resulting damage (in dollars) was estimated. Five test vehicles of each type were crashed, with
the results shown below. Research question: Are the mean crash damages the same for these three
vehicles?
Crash Damage ($)
Goliath Varmint Weasel
1,600 1,290 1,090
760 1,400 2,100
880 1,390 1,830
1,950 1,850 1,250
1,220 950 1,920
This question is from textbook
Click here to see answer by checkley77(7035) |
Question 160721This question is from textbook
: In a bumper test, three types of autos were deliberately crashed into a barrier at 5 mph, and the
resulting damage (in dollars) was estimated. Five test vehicles of each type were crashed, with
the results shown below. Research question: Are the mean crash damages the same for these three
vehicles?
Crash Damage ($)
Goliath Varmint Weasel
1,600 1,290 1,090
760 1,400 2,100
880 1,390 1,830
1,950 1,850 1,250
1,220 950 1,920
This question is from textbook
Click here to see answer by checkley77(7035) |
Question 160822This question is from textbook Elementary Statistics
: 5.2 (10, 14)
10. Determine whether the distribution represents a probability distribution. It not, state why.
x 20 30 40 50
p(x)1.1 0.2 0.9 0.3
14. State whether the variable is discrete or continuous.
The number of people who play the state lottery each day.
5.3 Problem # 19
A person decides to invest $50,000 in a gas well. Based on history, the probabilities of the outcomes are as follows.
Outcome p(x)
$80,000 (highly successful) 0.2
$40,000 (Moderately successful) 0.7
-$50,000 (Dry well) 0.1
Find the expected value of the investment. Would you consider this a good investment?
5.4 Problem # 16
16. Find the mean, variance, and standard deviation for the number of heads when 20 coins are tossed.
This question is from textbook Elementary Statistics
Click here to see answer by Fombitz(2113) |
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