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In a normal distribution what is the proportion of area between the z scores -2.09 and +.53
The National Association of Realtors estimates that 23% of all homes purchased in 2004 were considered investment properties. If a sample of 800 homes sold in 2004 is obtained what is the probabilit
In one particular investigation, a sample of 48 shear strength observations gave a sample mean strength of 17.17 N/mm2 and a sample standard deviation of 3.28 N/mm2. Find a lower confidence bound fo
Calculate a 90% confidence interval for the true average hole diameters, and give the interpretation.
Test the hypothesis that more female's use instagram than male's. Samples of 500 female and 500 male's were chosen, and 430 females and 390 males used instagram in the past week. Use the 10% signifi
One strategy for increased SAT exam scores is to take the test, study on weak areas, then retake the test. Based on the data presented from 11 students, does it appear retaking the exam results in i
IS there evidence to suggest the proportion of males who feel air travel is now safer is greater than the proportion of females? Complete this test specifically for proportions.
Insurance for an appliance costs $30 and will pay $330 if the insured item breaks within 2 years. The insurance company estimates that 3% of the insured items will break within 2 years. Let X be the
Carnival is exploring the possibility of offering a ferry service between Hilo and Maui, provided there is enough demand. Carnival randomly interviewed 210 commuters from the two islands, and 146 of
Assume that blood pressure readings are normally distributed with a mean of 122 and 17) a standard deviation of 6.4. If 64 people are randomly selected, find the probability that their mean blood pr
Determine the sample size that would be required to estimate the true proportion of defective chips if we wanted our estimate, p^, to be within 1.25% of the true proportion, with 99% confidence.
Subjects are randomly and independently assigned to two groups where one is giving the leading product and the other given a new drug about to be released. Subjects then record the time it takes to
In 1998 20% of university undergraduate students had at least one tattoo. A health practitioner obtains a random sample of 1029 university undergraduates and finds that 230 have at least one tattoo
IS there evidence to suggest the proportion of males who feel air travel is now safer is greater than the proportion of females? Complete your analysis based on odds ratios.
A multiple choice test consists of 5 questions each with 4 possible answers. What is the probability that a student will
Suppose you know that the distribution of sample proportions of the residents of one town over 70 years old in samples of 110 residents is normal with a mean of 0.12 and a standard deviation of 0.03
Compute the population standard deviation for this random variable and use your answer from the previous question in order to complete the following observation: Out of a population of 10000 custome
The mean of a normal distribution is 406 pounds. The standard deviation is 10 pounds. What is the area between 422 pounds and the mean of 406 pounds?
A national manufacturer of unattached garages discovered that the distribution of the lengths of time it takes two construction workers to erect the Red Barn model is normally distributed with a mea
What is wrong with this statement? High linear correlation proves that the explanatory variable (variable x) caused the response variable (y) to happen.
A bank wishes to estimate the mean credit card balance owed by its customers. The population standard deviation is estimated to be $297. If a 98 percent confidence interval is used and an interval o
If the null hypothesis that two means are equal is true, where will 99% of the computed z-values lie between?
What is the decision rule at the 0.01 level of significance to test if the new design increased the absorption amount of the sponge?
A student wanted to construct a 95% confidence interval for the average age of students in her statistics class. She randomly selected 12 students. Their average age was 20.7 years with a standard d
The proportion of junior executives leaving large manufacturing companies within three years is to be estimated within 2 percent. The 0.95 degree of confidence is to be used. A study conducted sever