Standard deviation - practice problems - page 4 of 6
Task: Work through each problem with care and demonstrate your solution process for each one.Number of problems found: 119
- 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 - Seed germination verification
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. - Car drive distribution
Five men drive to work together; 2 have a Škoda car, and the others have an Opel, Seat, and Hyundai. They always randomly choose which car to drive. Each of the five cars has an equal chance. The random variable X determines how many days the same charact - 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 Healthcare 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 - Chi square
A phone battery manufacturer claims that his battery lives are approximately normally distributed with a standard deviation equal to 0.9 years. Suppose a random sample of 10 of these batteries has a standard deviation of 1.2 years. Do you think that the s - 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 that this group performs le
- Three sigma rule
The height of trees in a given stand is known to be a quantity with a normal probability distribution with a mean value of 15 m and a variance of 5 m². Determine the interval in which there will be tree heights in such a stand with a probability of 90% - Corresponding Suppose that the country has had the following inflation rates over the past 14 years: 6.0; 6.7; 10.4; 11.9; 7.2;3.5; 8.4; 7.5; 2.8; 4.3; 1.9; 3.9; 0.9; 0.7. Use the χ² goodness-of-fit test to determine whether the random variable ξ corresponding to this
- A machine
A machine produces steel rods of normally distributed length, the mean length and the standard deviation being 50.0 cm and 0.5 cm, respectively. The rods do not conform to safety standards if they are either shorter than 49.1 cm or longer than 50.7 cm in - Five number summary
Find the five-number summary for these data and make a boxplot. 14,5,12,19,2,35,5,4,3,7,5,8 - Confidence interval A food testing laboratory in Abu Dhabi has been commissioned to estimate the amount of olive oil contained in 1-gallon tins purchased from a range of international olive oil producers. The manufacturers state that the standard deviation of the amount of o
- Probability
In the elections, 2400000 voters out of a total of 6000000 voters voted for party Z. Let us randomly select three voters and consider the random variable ξ={number of voters for party Z in the sample of three voters}. Determine a) the probability distribu - Probability In the election, 2400000 voters out of a total of 6000000 voters voted for party Z. Let us randomly select three voters and consider the random variable ξ={number of voters of party Z in the sample of three voters}. Determine a) the probability distributi
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