Statistics
posted by BEARHUG .
1) A Motor Company has purchased steel parts from a supplier for several years and has found that 10% of the parts must be returned because they are defective. An order of 25 parts is received. What are the mean and standard deviation of the defective parts?
A) Mean = 3.5; standard deviation = 2.5
B) Mean = 2.5; standard deviation = 1.5
C) Mean = 1.5; standard deviation = 2.5
D) Mean = 2.5; standard deviation = 3.5
2)Given a binomial random variable with n = 15 and = 0.4, find the following probability using the binomial table. P (6 < x < 10)
A) 0.0338
B) 0.1181
C) 0.0947
D) 0.3564

For 1).
Your values are the following:
p = .1, q = 1  p = .9, and n = 25
To find mean and standard deviation:
mean = np = (25)(.1) = ?
standard deviation = √npq = √(25)(.1)(.9)= ?
I'll let you finish the calculations to answer the question.
For 2).
Use the binomial table to determine your answer for the values given.
I hope this will help get you started.
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