Mean + standard deviation - practice problems - page 3 of 5
Number of problems found: 98
- The number 5
The number of hours per week the television is turned on is determined for each family in a sample. The mean of the data is 35 hours, and the median is 31.2 hours. Twenty-four families in the sample turned on the television for 20 hours or less for the we - Distribution 67074
The time required to complete the test has a normal distribution with a mean of 50 minutes and a standard deviation of 10 minutes. What percentage of students take the test within 30 minutes? - Three sigma rule
Stomach weights are normally distributed, with a mean of 1314g and a standard deviation of 113g. State the probability that a randomly selected stomach weighs more than 1118g. (Report the probabilities using at least four decimal places. ) - Probability 64174
The banker deals, on average, with five clients a day. Find the probability that the number of clients (in one day) will be greater than 4.
- 68-95-99.7 rule
Assume the resting pulse rates for a sample of individuals are normally distributed with a mean of 70 and a standard deviation of 15. Use the 68-95-99.7 rule to find the following quantities. a. Percentage of pulse rates less than 70 b. percentage of puls - Confidence 61774
What is the smallest number of men we would have to choose to estimate the mean height of men with an accuracy of +, - 0.5cm, and 95% confidence, assuming a standard deviation of 8cm? - Two methods
A teacher wishes two methods of teaching verbs to his English class. He divided the class randomly into two samples of 14 students each. Using Method 1, the students learned an average of 43.8 with a standard deviation of 4.6, while the second group (Meth - Two fertilizers
Jason is testing two fertilizers, Grow Well and Green Grow, so he went to a nursery and bought 50 tomato plants of the same variety. He planted all 50 plants in an identical environment. He then administered Grow Well to 25 of the tomato plants and Green - Z-score
The mean adult male pulse rate is 67.3 beats per minute, with a standard deviation of 10.3. Find the z-score for an adult male's pulse rate of 75. (Round the z-score to two decimal places. )
- Sample Proportion
In a California community college, 60% of students will transfer to a college in the CSU system. The number of students in a sample who will transfer follows a binomial distribution. Four hundred students are randomly selected from the college, and 224 of - Germination 55283
The supplier of spruce seeds for our nursery declares a germination rate of 80% for his goods. Verify this statement based on an experiment in which only 70 seeds germinated out of 100 randomly selected seeds. - Suppose 4
Suppose that 14% of all steel shafts produced by a certain process are nonconforming but can be reworked (rather than having to be scrapped). Consider a random sample of 200 shafts, and let X denote the number among these that are nonconforming and can be - Rich retirement
Health care issues are receiving much attention in both academic and political arenas. A sociologist recently surveyed citizens over 60 years of age whose net worth is too high to qualify for government health care but who have no private health insurance - Publishing company
Suppose you work for a publishing company, and before launching a new magazine targeting fashion-oriented consumers, your boss wants to hold a meeting with prospective advertisers. Assume that annual expenditures on magazine ads in this genre are normally
- Manufacturing company
A random sample of 8 manufacturing companies is selected from a population of manufacturing companies. The market values (in millions of rands) of these eight manufacturing companies are: 17 65 117 206 172 181 221 94 What is the lowest and highest market - A professor
A professor in a typing class found out that the average performance of an expert typist is 85 words per minute. A random sample of 16 students took the typing test, and we obtained an average speed of 62 words per minute with a standard deviation of 8. C - Unemployment rate
Over the last 16 years, the country's unemployment rate has changed according to the following frequency table: years of unemployment: 2 5 2 3 3 1 unemployment rate: 0.5 1 1.5 2 2.5 3 in % (percent). Determine the two-sided confidence interval for the var - Confidence Interval
The average grade of 50 senior students in a statistics class is 85, with a standard deviation of 10.2. In comparison, 60 senior students got an average of 80 with a standard deviation of 8.9. Can the difference in the mean grade be attributed to chance, - Performance comparing
A standardized test was administered to thousands of students with a mean score of 85 and a standard deviation of 8. A random sample of 50 students was given the same test and showed an average score of 83.20. Is there evidence to show that this group has
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