Binomial Distributions and Z-Scores
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1. A door to door salesperson believes that the probability of making a sale when a person is at home is 0.4 he visits 10 homes. When someone is at home find the probability of making a) exactly 7 sales b) more than 7 sales
2.For a binomial distribution with an n=200 and p=0.3 calculate the probability of obtaining between 50 and 70 successes inclusive in 200 trials .
Use the approximation to the binomial .
3.Find the area under the standard normal curve in each case below:
a) below a zscore of 2.5
b) between the z scores of -2.33 and 0.5
c) above the zscore of -1.3
4. A quality control tech is testing the accuracy of a certain type of resistor. He finds that the distribution of resistance is normal with a mean of 14.06 ohms and a standard deviation of 1.73 ohms
A) what is the probability that one of these resistors picked at random will have a resistance of 16 ohms or more?
B) What is the probability that one of these resistors picked at random will have a resistance between 13.06 ohms and 15.06 ohms, inclusive?
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Solution Summary
Binomial Distributions and Z-Scores are investigated. The solution is detailed and well presented.
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!"
- "Thank you"
- "Thank you very much for your valuable time and assistance!"
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