Standard deviation - practice problems - page 4 of 7
Task: Work through each problem with care and demonstrate your solution process for each one.Number of problems found: 128
- Two fertilizers
Jason is testing two fertilisers, Grow Well and Green Grow, on 50 tomato plants of the same variety planted in identical conditions. He applied Grow Well to 25 plants and Green Grow to the other 25. After four weeks, he measured the heights of the plants - Compare distributions
Which would you expect to be larger, the standard deviation of 5 random numbers picked from 1 to 47 in the California Super Lotto (CSL - write 1 as a result), or the standard deviation of 5 random numbers picked from 1 to 69 in the multi-state PowerBall L - A student 2
A student randomly selected 225 college students and asked whether they had eaten breakfast that morning before coming to campus. Fifty-seven students were at least 25 years old, and 30 had breakfast that morning. Of the 168 students younger than 25, 82 h - 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
- Respondents - chi-square
Asked respondents answered a question about their average net monthly wage. The given answers are in thousands €: 0.40; 0.60; 0.55; 0.68; 0.63; 0.70; 0.65; 0.75; 0.91; 0.63; 0.38; 0.39; 0.38; 0.74; 1.25; 1.10; 1.30; 1.15; 1.18; 1.13; 1.15; 1.19; 1.21. Usi - 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
- Chi-square The number of employees in the field of culture in country A and country B was compared. The following numbers of employees in thousands of persons were found: country A x/46/45/41/48/49/ country B y/128/135/147/152/148/. At the test level α=0.05 determin
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