92 Answered Questions for the topic Normal Distribution

Normal Distribution Statistics Standard Deviation Mean

10/03/15

Normal Distribution
Suppose that replacement times for washing machines are normally distributed with a mean of 10 years and a standard deviation of 1.4 years. Find the replacement time that separates the top 18% from... more
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06/25/15

How to find probability using only mean. Do I assume a std. dev. or certain probability distribution here?
The average time a customer spends waiting in the check-out line at Wal-Mart is seven minutes. If wait times are independent and constant, what is the probability the customer will spend between... more
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Normal Distribution Statistics

06/23/15

Suppose an exam had an average (mean) score of 55% and a standard deviation of 15%.
Suppose an exam had an average (mean) score of 55% and a standard deviation of 15%.   Table 6.3 Curving Grades A      1.5 standard deviations above the mean or higher B      0.5 to 1.5 standard... more
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Normal Distribution

06/14/15

How do I get the percent of adults from the survey slept longer than I did?
I slept 7.5 hours   A previous study administered to US adults showed that the amount of sleep (in hours) they get in a 24 -hour period is normally distributed with a mean of 7 hours and a... more
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06/06/15

Percentile Question!!
A random variable x has a normal distribution in the 50th percentile for x is 5. What is the mean of x?
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Normal Distribution Z Scores

04/23/15

in a standard normal distributuion, above which z-score do approximately 57% of the data lie?
in a standard normal distribution, above which z-score do approximately 57% of the data lie?
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Normal Distribution Statistics Probability

04/18/15

find the probability that, if two apples are chosen at random, the first weighs at least 20g more than the second
Normally distributed mean = 150g standard deviation = 16g
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Normal Distribution

04/04/15

In a certain normal distribution of scores, the mean is 50 and the standard deviation is 6. Find the z-score corresponding to a score of 60.
I need help with this math problem for me to graduate high school. I really really need the help.
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Normal Distribution Statistics Statistics Question Stats

02/21/15

Three complicated statistics (Normal Distribution) questions
1) The lengths in minutes of feature films for the current year follow a normal distribution with a mean of 109 minutes and a standard deviation of 12 minutes. What percentage of feature films in... more
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Normal Distribution Standard Deviation

12/22/14

What are the cutoffs for B?
Suppose exam scores form an approximately normal distribution that has μ = 500 points and σ = 100 points. Letter grades on the exam were distributed as follows: Ds made up 16% of the exam, Cs 30%,... more
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Normal Distribution Statistics Question

11/27/14

Need help.
The mean gas mileage for a hybrid car is 56 miles per gallon. Suppose that the gasoline mileage is approximately normally distributed with a standard deviation of 3.3 miles per gallon. (a) What... more
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Normal Distribution Probability Random Variable

11/23/14

how do I calculate the probability X1 > X2 where X1 and X2 are independent, normally distributed random variables?
how do I calculate the probability X1 > X2 where X1 and X2 are independent, normally distributed random variables?
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Normal Distribution

11/14/14

Statistics normal distribution
The gpa at best university has a normal distribution with a mean of 2.46 and a standard deviation of 1.13. Approximately what percent of the best university students have their gpa below 1.54?
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Normal Distribution Z Score

10/17/14

The average woman's height is 65 in. with a stdev of 3.5 in. How many women out of 10,000 would be taller than the 70 in. tall woman?
z- Score is 1.4
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09/02/14

Finding the percentage from the normally distributed mean and standard deviation? Help please :)
So, this is the question I'm have difficultly working out, I've come close to the answer but my calculations are clearly going wrong, anyway, here's the question and the help would be much... more
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Normal Distribution Statistics Normal Curve

07/30/14

How do you solve these questions?
Hello! I would like to ask on how to solve these questions in Statistics. The topic is about the normal distribution curve. (Before starting, I do not have a picture of the z table to show you what... more
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Normal Distribution Statistics Percentage

05/14/14

Percentage question
Assume that red blood cell counts of women are normally distributed with a mean of 4.577 and a standard deviation of 0.382. What percentage of women have red blood cell counts in the normal range... more
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