Question 678723:
The head accountant at Raglan resources is concerned over the clerical errors on outgoing invoices and suspects that more than 20% of these invoices contain at least one error. In a random sample of 500 invoices, 120 are found to contain at least one error. Do these data support the account’s views? Let alpha=.05
2. A random sample of 36 radio stations is selected in order to estimate the average charge for the same fixed-length spot announcement. The sample mean and standard deviation are $20.00 and $8, respectively. Assume that the charge made by all radio stations of the type sampled area approximately normally distributed. Construct the 95% confidence interval for the mean.
3. A random sample of 64 bearings produced by a machine has a mean diameter of 1.5 inches with a standard deviation of 0.1 inch. Constructs a 90% confidence interval for the mean diameter of ball the bearings?
4. Students working for a doctorate in education wishes to draw samples of high school freshmen in order to estimate the average amount of time per day they spend studying. A standard deviation of 25 minutes was reported by another researcher conducting a similar study. The students want a 95% level of confidence in calculating the population mean. How large should the sample be if the estimate needs to be within minutes of the true mean?
5. Suppose it is known that the time spent by customers’ in a fast- food restaurant is a normally distributed variable with a, mean of 16 minutes and a standard deviation of 4 minutes. What is the probability that a random sample of 25 customers will yield a mean between 15 and 18 minutes, inclusive?
The credit manager of the Adler department store chain believes that average age of his charge-account customers is less than 30 years. A random sample of 100 charge-account customers reveals a mean age of 27 years and a standard deviation of 5 years. Do these data provide sufficient evidence to support the credit manager’s belief? Let alpha=.05
7. Nothings the declining popularity of public billiard parlors, a recreation specialist hypothesizes that 12% of the homes in a certain area have pool tables. In a random sample of 100 homes in the areas, 16 found to have pool tables. Do these data support the recreation specialist’s contention? Let alpha=.01
8. A certain type of yarn is manufactured under specifications that the mean tensile strength must be 25 pounds. A random sample of the 16 specimens yields a mean tensile strength of 24 pounds and a sample standard deviation of 3.2 pounds. Can we conclude from these data that mean tensile strength for the population is less than 25 pounds?
9. In a certain population, 45 percent of the adults go to church regularly. If a random sample of 200 adults is selected from this population, what is the probability that the sample proportion will exceed 0.50?
10. During a winter shortage of matural gas, citizens are asked to lower the thermostats in their homes to 65 degree or less. A random sample of 300 households in a mid-western town reveals that 225 have
Found 2 solutions by stanbon, duotmto:
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! A used car salesperson estimates the probabilities for the number the number of cars sold in a week as follow-
number—0, 1, 2 ,3,4,5
Probability-.05,.20,.35,.25,.10,.05
a) What is the probability for a given week that four or more cars will be sold?
P(4 or more sold) = P(4 sold) + p(5 sold) = 0.10 + 0.05 = 0.15
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b) Find the expected number of cars sold in a week
Multiply each "number value" by its corresponding probability.
Add those 6 products to get the expected number sold
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c) What is the probability that the salesperson will sell more than 2 cars in a given week?
P(sell more than 2) = P(3)+P(4)+p(5) = 0.4
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d) For a period of 3 weeks, what is the probability that salesperson will sell more than 2 cars every week?
Ans: 0.4^3 = 0.064
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Cheers,
Stan H.
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Answer by duotmto(2) (Show Source):
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