Tutors Answer Your Questions about Probability-and-statistics (FREE)
Question 327128: The weights of the fish in a certain lake are normally distributed with a mean of 10 lb and a standard deviation of 6. If 4 fish are randomly selected, what is the probability that the mean weight will be between 7.6 and 13.6 lb?
Click here to see answer by stanbon(57246)  |
Question 327126: An event A will occur with probability 0.5. An event B will occur with probability 0.6. The probability that both events A AND b will occur is 0.1.
the conditional probability of A given B is:
a- 0.3
b- 0.2
c- 1/6
d- cannot be determined from the info given
someone please show me the way to get the right answer
thank you so much
you are all so helpful
Click here to see answer by stanbon(57246) |
Question 327122: if the letters A,B,C,D,E and F are to be used in a five letter code, how many
different codes are possible if repetitions ARE PERMITTED.
A- 625
B- 720
C- 7776
D- 1296
ANSWER C IS POSSIBLE IF REPETITIONS ARE NOT PERMITTED. BUT WHAT IF THEY ARE?
PLEASE HELP ME
Click here to see answer by galactus(183)  |
Question 327037: Twelve $5-bills, eight $10-bills, and five $20-bills are put into a bag and shaken up. You get to reach in and pull out two of the bills without looking. What is the probability you get a total of at least $20?
a 46% b 54% c 66 2/3% d 33 1/3% e 60%
Click here to see answer by Fombitz(13828)  |
Question 327173: The measure of the length of the index finger of a human right hand is normally distributed with a mean of 6cm and a standard deviation of 0.5cm What is the probability that the index finger length of a randomly selected person will between 5cm and 7.5cm?
a) .9759 b) .0241 c) .95 d) 1.0 e) none of the above
Please show work so i can understand
Click here to see answer by Fombitz(13828) |
Question 327158: I have two questions that I am in dire need of answers to. I have been stumped for 3 days:
A math teacher gives two different tests to measure students' aptitude for math. Scores on the first test are normally distributed with a mean of 20 and a standard deviation of 5.3. Scores on the second test are normally distributed with a mean of 68 and a standard deviation of 11.6. Assume that the two tests use different scales to measure the same aptitude. If a student scores 27 on the first test, what would be his equivalent score on the second test? (That is, find the score that would put him in the same percentile.)
a) 75.4 b) 81.3 c) 83.3 d) 84.1
The law firm of Dewey, Cheetham, and Howe has a pool of candidates wishing for internship in the law firm. The law firm has decided to test each candidate on his or her ability to win a nuisance lawsuit. Candidates who score in the top 33% will be given an internship. The law firm has issued similar tests in the past and knows that the average score is 80 (out of 100), the standard deviation is 10, and that test scores are normally distributed. What is the minimum score that a candidate must earn in order to place in the top 33%?
a) 81.25 b) 84.40 c) 86.30 d) 88.60
Click here to see answer by scott8148(6628)  |
Question 327207: The demand for apple pies at the bakery is shown in the table. What is the probability that the demand next Saturday will be 9 apple pies or more?
Demand for Apple Pies on Saturday/ Probability
4 / .01
5 / .03
6 / .07
7 / .12
8 / .25
9 / .26
10 / .17
11 / .05
12 / .04
= 1.00
a. .26
b. .74
c. .75
d. .48
e. .52
Click here to see answer by Fombitz(13828) |
Question 327230: Instructions: For each exercise, use Excel, or MegaStat to make an attractive, well-labeled time-series line chart. Adjust the Y-axis scale if necessary to show more detail (since Excel usually starts the scale at zero). If a fitted trend is called for, use Excel’s option to display the equation and R2 statistic (or MAPE, MAD, and MSD in MINITAB). Include printed copies of all relevant graphs with your answers to each exercise.
(a) Plot the data on full-time mathematics graduate students. (b) Would a fitted trend be helpful? Explain. (c) Make a forecast for 2003, using a trend model of your choice (or a judgment forecast).
MathGrads
Full-Time Mathematics Graduate Students, 1993–2002
Year Total
1993 10,525
1994 10,185
1995 9,761
1996 9,476
1997 9,003
1998 8,791
1999 8,838
2000 9,637
2001 9,361
2002 9,972
Click here to see answer by Fombitz(13828) |
Question 327199: The probability that house sales will increase in the next 6 months is estimated to be 0.25 the probability that the interest rates on the housing loans will go up is estimated to 0.7 the probability that house sales and interest rates will go up in the next 6 months is estimated to be 0.20 the probably that house sales or interest rates will increase during in the 6 months is
a) 0.75 b)0.85 c) 0.705 d)0.90
Click here to see answer by stanbon(57246) |
Question 327193: A teacher has prepared a 6-item test with the first three items being true or false and the last three items being multiple-choice with four choices each. What is the probability that a student will score100% if every answer is chosen at random?
Click here to see answer by stanbon(57246) |
Question 327170: The probability that house sales will increase in the next 6 months is estimated to be .25. The probability that the interest rates on housing loans will go p is estimated to 0.7 The probability that house sales and interest rates will go up in the next 6 months is estimated to be 0.20 The probability that house ales or interest rates will increase during in the 6 months is
a) .75 b).85 c) .705 d) .90
Click here to see answer by stanbon(57246) |
Question 327144: Question 327103: I am wondering if I could get confirmation for this problem. I think you would square the -.6 to get -.36. But I am not sure.
If the correlation between a response variable Y and explanatory variable X is -0.6, what is the value that defines how much variation in Y is explained by X?
A) 6%
B) 36%
C) - 36%
D) - 6%
Thanks,
Maria
Hi, I am having a problem with the solution to the problem. Stanbon, you said You are give r=0.6
So, r^2 = 0.36 = 36%
In the question it gives x= -0.6, does that turn into a positive 0.6 somewhere to get the r=0.6?
Thanks for explaining this one to me.
Maria
Click here to see answer by stanbon(57246) |
Question 327243: A study of Furniture Wholesales, Inc. 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 Furniture Wholesales 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 working days of the receipt of the invoice. What percent of customers will earn this discount
Click here to see answer by stanbon(57246) |
Question 327052: Is the mean salary of accountants who have reached partnership status higher than that for accountants who are not partners? A sample of 15 accountants who have the partnership status showed a mean salary of $82,000 with a standard deviation of $5,500. A sample of 12 accountants who were not partners showed a mean of $78,000 with a standard deviation of $6,500. At the 0.05 significance level can we conclude that accountants at the partnership level earn larger salaries
a. State the null and alternate hypotheses.
b. State the decision rule.
c. Compute the value of the test statistic.
d. Compute the p-value.
e. What is your decision regarding the null hypothesis? Thanks
Click here to see answer by stanbon(57246) |
Question 327288: I was wondering if I could get some help with this problem.
A regression was done for 20 cities with latitude as the explanatory variable (x) and average January temperature as the response variable (y). The latitude is measured in degrees and average January temperature in degrees Fahrenheit. The latitudes ranged from 26 (Miami) to 47 (Duluth) The regression equation is
y = 49.4 - 0.313x
The city of Miami, Florida has latitude 26 degrees with average January temperature of 67 degrees Fahrenheit.
1. What is the estimated average January temperature for Miami, and
2. based on the regression equation, what is the residual?
A) Estimated January temperature is 36.88 and the residual is 11.88
B) Estimated January temperature is 41.3 and the residual is - 25.7
C) Estimated January temperature is 36.88 and the residual is - 11.88
D) Estimated January temperature is 41.3 and the residual is 25.7
I am at a loss trying to figure this out.
Thanks,
Dave
Click here to see answer by stanbon(57246) |
Question 326994: A mini license plate for a toy car must consist of two letters followed by a one digit odd number. Each letter must be a K or a Q. Repetition of letters is not permitted.
1. Use the counting principle to determine the number of points in the sample space.
2. Construct a tree diagram
3. List the sample space.
4. Determine the exact probability of creating a mini license plate with a 3.
Click here to see answer by stanbon(57246) |
Question 327354: There are four green blocks and four red blocks in a bag.
a) What is the probability of selecting a red block, keeping it, then selecting
another red block?
b) What is the probability of selecting a green block, replacing it, then selecting a red block?
Click here to see answer by stanbon(57246) |
Question 327332: If a researcher wishes to determine whether there is evidence that the mean family income in the US is greater than 30,000 then:
a) A one tailed test should be utilized
b) a two tailed test should be utilized
c) Either a one tailed or a two tailed test could be utilized since they are equivalent
d) none of the above
Please explain so I can understand Thanks.
Click here to see answer by stanbon(57246) |
Question 326904: a roulette wheel has 38 slots in which the ball can land. two of the slots are green, 18 are red, 18 are black. the ball is equally likely to land in any slot. the roulette wheel is going to be spun twice and the outcome of the two spins are independant.
the probability that it lands on red the first time and black the second time is:
a- 0.2136
b- 0.2244
c- 0.2500
d- 0.5000
Click here to see answer by stanbon(57246) |
Question 326839: If casino Keno were fair, how much should it pay to a player who bets $2 to bet 6 numbers and matches 4 numbers? The odds against matching 4 numbers in casino Keno when you bet 6 numbers are about 34 to 1.
Click here to see answer by stanbon(57246) |
Question 326800: 3. The height of adult males is normally distributed with mean of 70 inches and a standard deviation of 2.6 inches.
a) If all samples of size 144 are drawn, what should the mean of the sample means be according to the Central Limit Theorem? (5 points)
b) If all samples of size 144 are drawn, what should the standard deviation be according to the Central Limit Theorem? (10 points)
Click here to see answer by stanbon(57246) |
Question 326798: 8. In order to test H0: μ = 40 versus H1: μ > 40, a random sample of size n = 25 is obtained from a population that is known to be normally distributed.
a) If the sample mean is determined to be 42.3 and s = 4.3, compute the test statistic.
b) If the researcher decides to test this hypothesis at the α = 0.1 level of significance, determine the critical value.
c) Draw a normal curve that depicts the critical region.
d) Will the researcher reject the null hypothesis?
Click here to see answer by stanbon(57246) |
Question 327484: Assume that a person spins a pointer and is awarded an amount based on the following: half of the spinner's area results in winning $8, a quarter of the spinner results in winning $12, and a quarter of the spinner results in winning $1. Determine the person's expectation.
Click here to see answer by stanbon(57246) |
Question 327494: Hi ive been having alot of trouble figuring out the answer to this question i mean i know the answer is 2/7 but i just dont get how... The question is: an urn contains 4 orange marbles and 3 pink ones. Two marbles are drawn at random. what is the probability that both marbles are purple if the marbles are drawn Without Replacement? It would help if you showed your work so i can try to understand the procedure :o)
thanks,
Oskar :)
Click here to see answer by stanbon(57246) |
Question 327494: Hi ive been having alot of trouble figuring out the answer to this question i mean i know the answer is 2/7 but i just dont get how... The question is: an urn contains 4 orange marbles and 3 pink ones. Two marbles are drawn at random. what is the probability that both marbles are purple if the marbles are drawn Without Replacement? It would help if you showed your work so i can try to understand the procedure :o)
thanks,
Oskar :)
Click here to see answer by galactus(183) |
Question 327496: An urn contains 4 purple marbles and 3 pink ones. Two marbles are drawn from the urn. what is the probability that both marbles are purble Without Replacement
Sorry the question i just posted was incorrect This is the correct one
Thanks,
Oskar :o)
Click here to see answer by jim_thompson5910(28504) |
Question 327495: An urn contains 4 purple marbles and 3 pink ones. Two marbles are drawn from the urn. what is the probability that both marbles are purble
Sorry the question i just posted was incorrect This is the correct one
Thanks,
Oskar :o)
Click here to see answer by galactus(183) |
Question 327628: the probability that a car will have a flat tire while driving through a certain tunnel is 0.00006. use the poissan distribution to approximate the probability that among 15000 cars passing through the tunnel at most two will have a flat tire.
Click here to see answer by galactus(183) |
Question 327642: 1/10 of men and 1/7 of women are color-blind. A person is randomly selected.
Assume males and females to be in equal numbers.
What is the probability that the selected person is color-blind?
Click here to see answer by Theo(3458)  |
Question 328001: A population of small town is 250. Out of 250, 150 are adults and one of those is a millionaire who makes $ 8 million per year. The average salary of that town is $100,020 per year. What is the average salary for remaining 149 adults in that town?
Answer
A) $ 52000
B) $47000
C) $ 51000
D) $ 49000
Click here to see answer by josmiceli(9661)  |
Question 285974: In a certain microwave oven on high power, the time it takes a randomly chosen kernel of popcorn to pop is normally distributed with a mean of 140 seconds and a standard deviation of 25 seconds. What percentage of kernels will fail to pop if the popcorn is cooked for
(a) 2 minutes? (b) 3 minutes? (c) if you wanted 95% of the kernels to pop, what time would you allow? (d) If you wanted 99% to pop?
Click here to see answer by huntingdonstudent(1) |
Question 328027: The source of federal government revenue for a specific year is
50% from individual income taxes
32% from social insurance payroll taxes
10% from corporate income taxes
3% from excise taxes
5% other
If revenue is selected at random, what is the probability that it comes from individual or corporate income taxes?
Click here to see answer by rapaljer(4667)  |
Question 327966: A ship can successfully arrive at its destination if it engine and satellite
navigation system do not fail en route. If the engine and navigation system are known to fail independently with respective probabilities of 0.05 and 0.001,what is he probability of a successful arrival?
Click here to see answer by Fombitz(13828) |
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