Question 436527: I have Dyscalclia (Math Dyslexia) and I am in tears trying to figure these out. Please help me get some extra credit points.
A company has determined that the mean number of days it takes to collect on its accounts receivable is 36 with a standard deviation of 11 days. What is the probability that a single AR account takes more than 30 days to collect?
The Dilmart Company has 8,000 parts in inventory. The mean dollar value of these parts is $10.79 with a standard deviation equal to $3.34. Suppose the inventory manager selected a random sample of n = 64 parts from the inventory and found a sample mean equal to $11.27. What is the probability of getting a sample mean at least as large as $11.27?
A vaccine is 90 percent effective. What is the probability that it is effective for two or more individuals out of 20 individuals? Use the normal approximation to the binomial distribution.
The quality control manager of a tire company wishes to estimate the tensile strength of a standard size of rubber used to make a class of radial tires. The historical population standard deviation is 35 pounds. A random sample of 61 pieces of rubber from different production batches is subjected to a stress test. The test measures the force needed to break the rubber in pounds. According to the sample results, the average pressure is 238.4 pounds. Determine the 98% confidence interval.
The average weight of an airline passenger’s suitcase is 45 pounds. The standard deviation is 2 pounds. If 17% of the suitcases are overweight, find the maximum weight allowed by the airline. Assume the variable is normally distributed. See curve drawn on the board.
Recently, a report in a financial journal indicated that the 90 percent confidence interval estimate for the proportion of investors who own one or mutual funds is 0.9 with a margin of error of ± 0.02 points. Given this information, calculate the required sample size.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! A company has determined that the mean number of days it takes to collect on its accounts receivable is 36 with a standard deviation of 11 days. What is the probability that a single AR account takes more than 30 days to collect?
-----
z(30) = (30-36)/11 = -6/11
P(x > 30) = P(z > -6/11) = normalcdf(-6/11,100) = 0.7073
----------------------------------------------------------------
The Dilmart Company has 8,000 parts in inventory. The mean dollar value of these parts is $10.79 with a standard deviation equal to $3.34. Suppose the inventory manager selected a random sample of n = 64 parts from the inventory and found a sample mean equal to $11.27. What is the probability of getting a sample mean at least as large as $11.27?
--------------
Note: The sample of size 64 have a standard
deviation of 3.34/sqrt(64) = 0.4175
-------------
z(11.27) = (11.27-10.79)/0.4175 = 1.1497
P(x-bar >=11.27) = P(z>= 1.1497) = normalcdf(1.1497,100) = 0.1251
------------------------------------------------------------------------
A vaccine is 90 percent effective. What is the probability that it is effective for two or more individuals out of 20 individuals? Use the normal approximation to the binomial distribution.
---
Find P(19.5<= x <=20.5) when u = np = 20*0.9 18 and
std = sqrt(20*0.9*0.1) = 1.3416
----
z(19.5) = (19.50-18)/1.3416 = 1.1181
z(20.5) = (20.5-18)/1.3416 = 1.8634
------
Ans = P(1.1181<= z <=1.8634) = 0.1006
=================
Cheers,
The quality control manager of a tire company wishes to estimate the tensile strength of a standard size of rubber used to make a class of radial tires. The historical population standard deviation is 35 pounds. A random sample of 61 pieces of rubber from different production batches is subjected to a stress test. The test measures the force needed to break the rubber in pounds. According to the sample results, the average pressure is 238.4 pounds. Determine the 98% confidence interval.
The average weight of an airline passenger’s suitcase is 45 pounds. The standard deviation is 2 pounds. If 17% of the suitcases are overweight, find the maximum weight allowed by the airline. Assume the variable is normally distributed. See curve drawn on the board.
Recently, a report in a financial journal indicated that the 90 percent confidence interval estimate for the proportion of investors who own one or mutual funds is 0.9 with a margin of error of ± 0.02 points. Given this information, calculate the required sample size.
|
|
|
