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# Stats!!! watch

1. My main problems question 2, and I keep getting conflicting answers for q1. Any help would be appreciated!

Q1) X is a random variable which follows a Binomial distribution. The mean of the distribution is 20 and the standard deviation is 4. The number of trials is 100.

a) Calculate the probability that X is equal to 15.

b) What is the probability that X is less than or equal to 62?

c) A researcher chooses a value of X called ‘A’ such that the 20% of the distribution lies below A. What is the value of A?

Q2) The population variance of the distribution for Xis 100. Two random samples of size n1 and n2 are repeatedly taken from the population (with replacement). The sample means for sample size n1 and sample size n2 have the following distributions:

a)​What are the sizes of samples 1 and 2?

b)​What is the best estimate of the mean of the population, μ?

d)​A sample A is taken from the population. It is of size n1. Calculate the probability that the sample mean is within 1 unit of the population mean.

Q3) Large random samples of size n are taken (with replacement) from a population which follows a uniform distribution with mean 25 and a standard deviation of 22.
a) What is the expected value of the sample mean?​​​​​​​
b) Can the Central Limit Theorem be applied in this case?​​​​​​​
c) The probability that a sample mean is greater than 27 is 0.1587. Find n.​​
d) If the population followed a Chi-Squared distribution, how would you approach part c) of this question?​​​​​

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2. (Original post by JellyCat99)
My main problems question 2, and I keep getting conflicting answers for q1. Any help would be appreciated!
Well, uhm - mind showing us your working?

3. I'm stuck in 1c and 2d, I don't even know where to start... I don't know what it means in 2d when it says 1 unit of the population mean??

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4. (Original post by JellyCat99)

I'm stuck in 1c and 2d, I don't even know where to start... I don't know what it means in 2d when it says 1 unit of the population mean??

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How can you use the information given in 1c to find out what A is?

If something is within 1 unit of the mean, what does this tell you about the values of that something?
5. Ahhh, ECON1007 i see!
6. (Original post by Student0070)
Ahhh, ECON1007 i see!
Yup, you know it! Don't suppose you've solved 1c??

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7. Have you done question 3? If so what did you get?

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Updated: March 13, 2016
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