Standard distribution, deviation, etc.
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15. If P(A) = 0.4, P(B| A) = 0.35, P(A  B) =0.69, then P(B) =
a. 0.14
b. 0.43
c. 0.75
d. 0.59
18. If X and Y are mutually exclusive events with P(X) = 0.295, P(Y) = 0.32, then P(XY) =
a. 0.0944
b. 0.6150
c. 1.0000
d. 0.0000
27. For a standard normal distribution, the probability of z  0 is
a. zero
b. -0.5
c. 0.5
d. one
28. Z is a standard normal random variable. The P(-1.96  Z  -1.4) equals
a. 0.8942
b. 0.0558
c. 0.475
d. 0.4192
29. The weight of football players is normally distributed with a mean of 200 pounds and a standard deviation of 25 pounds. The probability of a player weighing less than 250 pounds is
a. 0.4772
b. 0.9772
c. 0.0528
d. 0.5000
31. A population has a standard deviation of 16. If a sample of size 64 is selected from this population, what is the probability that the sample mean will be within 2 of the population mean?
a. 0.6826
b. 0.3413
c. -0.6826
d. Since the mean is not given, there is no answer to this question.
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Solution Summary
The solution is provided in an attachment and includes explanations to the multiple choice answers and references.
Education
- BSc , Wuhan Univ. China
- MA, Shandong Univ.
Recent Feedback
- "Your solution, looks excellent. I recognize things from previous chapters. I have seen the standard deviation formula you used to get 5.154. I do understand the Central Limit Theorem needs the sample size (n) to be greater than 30, we have 100. I do understand the sample mean(s) of the population will follow a normal distribution, and that CLT states the sample mean of population is the population (mean), we have 143.74. But when and WHY do we use the standard deviation formula where you got 5.154. WHEN & Why use standard deviation of the sample mean. I don't understand, why don't we simply use the "100" I understand that standard deviation is the square root of variance. I do understand that the variance is the square of the differences of each sample data value minus the mean. But somehow, why not use 100, why use standard deviation of sample mean? Please help explain."
- "excellent work"
- "Thank you so much for all of your help!!! I will be posting another assignment. Please let me know (once posted), if the credits I'm offering is enough or you ! Thanks again!"
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