Questions on Normal Probability Models. Probability and area under the curve answered by real tutors!

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Question 1193109: P(x<69.1)=
Click here to see answer by ikleyn(52784)

Question 1193884: Suppose Z is a standard normal random variable and let Y = aZ +b, where a > 0 and b are constants.
(a) Show that MY (t) = exp {bt +
a
2
t
2
2
}.
(b) Calculate the probability, P(1.2 < Y < 7) if Y ∼ N(3, 4
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Question 1194055: Compute the area under the normal curve with the following data: μ=35 and σ=3, when x is more than 30 but less than 40. Round to two decimal places and do not include the "percent sign". *

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Question 1195825: Suppose commute times in a large city are normally distributed and that 62.50% of commuters in this city take more than 20 minutes to commute one-way. If the standard deviation of such commutes is 6.5 minutes, what is the mean commute?
Click here to see answer by Boreal(15235)

Question 1197033: The elevator at the Matthews Building of the University of New South Wales starts with 10 passengers at the ground and makes stops at each of the 14 floors above. Assuming that it is equally likely that a passenger gets off at any of these 14 floors, what is the probability that at least two of these passengers will get off at the same floor?
Click here to see answer by ikleyn(52784)

Question 1197799: A bag of marbles contains 6 blue, 7 red, and 8 orange marbles. What is the probability of picking a red marble and then an orange marble if you do not replace the first marble?
Click here to see answer by Alan3354(69443)

Question 1200896: Fair six sided die is rolled four times was the probability that the sequence of rolls is 6234
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Question 1201071: 123 year 11 students chose the courses they wanted at the school prom dinner. 75 chose a starter, 106 chose a main course and 81 chose a dessert. 67 chose a main course and dessert, 64 chose a starter and a main course while 49 chose a starter and dessert. Everybody ordered at least one course. Find the probability that a student chosen at random chose all three courses
Click here to see answer by ikleyn(52784)

Question 1201663: Please solve this equation:
The mean of a normal probability distribution is 300; the standard deviation is 16.
a. About 68% of the observations lie between what two values?
______________

b. About 95% of the observations lie between what two values?
___________________________
c. Practically all of the observations lie between what two values?
_____________________

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Question 1201898: A class consisting of 8 men and 7 women we're 2 selected randomly to represent the class in a dabate find the probability that the 2 selected are (I) both men (ii) both woman (iii) of the same Sex (iv) of the different Sex.
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Question 1202367: A box contains 4 white shirts and 3 blue shirts. Two shirts are picked at random from the box, one at a time without replacement. What is the probability that the first chip is white and the second chip is blue?
Click here to see answer by greenestamps(13200)

Question 1202499: The Great Pyramid of King Khufu was built of limestone in
Egypt over a 20-year time period from 2580 bc to 2560 bc.
Its base is a square with side length 230 m and its height
when built was 147 m. (It was the tallest man-made structure
in the world for more than 3800 years.) The density of
the limestone is about 2400 kg/m3
(a) Estimate the total work done in building the pyramid.
(b) If each laborer worked 10 hours a day for 20 years, for
340 days a year, and did 250 J/h of work in lifting the
limestone blocks into place, about how many laborers
were needed to construct the pyramid?
Click here to see answer by ikleyn(52784)

Question 1203498: A company estimates that 1% of their products will fail after the original warranty period but within 2 years of the purchase, with a replacement cost of $350.
If they want to offer a 2 year extended warranty, what price should they charge so that they'll break even (in other words, so the expected profit will be 0)
$

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Question 1204513: The diameter of a brand of tennis balls is approximately normally distributed, with a mean of 2.54 inches and a standard deviation of 0.05 inch. A random sample of 10 tennis balls is selected. What is the probability that the sample mean is less than 2.53 inches?
Click here to see answer by Theo(13342)

Question 1204966: Business Weekly conducted a survey of graduates from 30 top MBA programs. On the basis of the survey, assume the mean annual salary for graduates 10 years after graduation is 169000 dollars. Assume the standard deviation is 36000 dollars. Suppose you take a simple random sample of 91 graduates. Assume the population is normally distributed.

Note: You should carefully round any intermediate values you calculate to 4 decimal places to match wamap's approach and calculations.
Find the probability that a single randomly selected salary exceeds 166000 dollars.
P(X > 166000) = 0.2023
Enter your answer as a number accurate to 4 decimal places.
Find the probability that a sample of size 91 is randomly selected with a mean that exceeds 166000 dollars.
P(x > 166000) =
Enter your answer as a number accurate to 4 decimal places.
I did the first part but can't find P(xbar > 166000) with sample of 91
part but can not figure out the bottom because when I do it I get a number that does not / can not exist for this problem. please help

Click here to see answer by math_tutor2020(3817)

Question 1205510: A box contains 10 chocolates, of which 4 are dark chocolates and 6 are milk chocolates. If two chocolates are randomly selected without replacement, what is the probability of getting one dark chocolate and one milk chocolate in any order?
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Question 1205865: Three person are contesting elections from Same consistuency. Mr. X and Mr. Y have same chance of "but Mr. Z has twice the chance winning, but Mr. Z either Mr. X or Mr.Y. What is the probability that;
(i) Mr. Z wins.
(ii) Mr. X does not win.

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Question 1206682: You have a deck with 52 cards. what is the probability of you pulling a 7 of spades?
Click here to see answer by MathLover1(20850)

Question 1200376: In a suburban community, 30% of the households use Brand A toothpaste, 27% use Brand B, 25% use Brand C, and 18% use Brand D. In the foul groups of households, the proportions of residents who learned about the brand they use through television advertising are as follows Brand A, 0.10; Brand B, 0.05; Brand C, 0.20; and Brand D, 0.15. In a household selected at random from the community, it is found that residents learned about the toothpaste through television advertising. What is the probability that the brand of toothpaste used in the household is (a) A, (b) B, (c) C, (d)D?

Click here to see answer by GingerAle(43)

Question 1199038: Pasien Dirawat di IGD Rumah Sakit Di sebuah rumah sakit, sampel 8 minggu dipilih, dan ditemukan bahwa rata-rata 438 pasien dirawat di IGD setiap minggu. Standar deviasinya adalah 16. Temukan interval kepercayaan 99% dari rata-rata sebenarnya Asumsikan variabel terdistribusi normal.
Click here to see answer by textot(100)

Question 1170505: A machine fills pop bottles with a standard deviation of 25 mL no matter what the setting is for the mean. At how many mililiters should the mean be set, so that 90% of the bottles will contain at least 500 mL?
Click here to see answer by CPhill(1959)

Older solutions: 1..45, 46..90, 91..135, 136..180, 181..225, 226..270