Percentages + standard deviation - practice problems
Number of problems found: 24
- Lightbulbs
The physical plant at the main campus of a large state university recieves daily requests to replace fluorescent lightbulbs. The distribution of the number of daily requests is bell-shaped and has a mean of 48 and a standard deviation of 10. Using the emp - A random 2
A random sample of 40 families has an average water consumption of 29 cubic meters per month, with a sample standard deviation of 8 cubic meters. Give the 90% confidence interval for the mean usage of water per month. - Bell curve A company has a policy of retiring company cars; this policy looks at the number of miles driven, purpose of trips, style of car, and other features. The distribution of the number of months in service for the fleet of cars is bell-shaped and has a mean o
- IQ scores
IQ scores are normally distributed with a mean of 100 and a standard deviation of 15. What percentage of the population scores higher than 125 on an IQ test?
- Suppose 12
Suppose in a physics test involving 30 students, and four scored 75%, eight scored 60%, twelve scored 50%, and six scored 30%. Calculate the mean of the group and the standard deviation. - A random
A random sample of 225 nails in a manufacturing company is gathered. The engineer specified that the specified length of a nail must be 8 cm having a standard deviation of 0.04 cm. It shows from the sample that the average length of the nails is 8.055 cm. - Suppose 8
Suppose the scores on a test have a normal distribution with X=74 and a standard deviation of s=18. What percentage of students have scores higher than 90? What percentage of students have scores between 70 and 85? Twenty percent of the students do better - Confidence interval When checking the use-by date of a specific type of canned meat in warehouses of meat industry products, 340 canned goods were randomly selected, and it was found that 63 of them had passed their warranty period. Establish a 95% confidence interval to est
- Normally distributed
Suppose the height of male youngsters is normally distributed with a mean of 60 inches and a standard deviation of 10. what percentage of the boy's height would we expect to be between 44 and 75, less than 49, and 76 and more?
- Quartile statistics
Use the following data, which was obtained from a study of weights of adult men, to answer problems: Mean ; 192 lb ; First quartile ; 178lb Median; 185lb ; Third quartile ; 232 lb Mode ; 180 lb ; 86th percentile ; 239 lb Standard Deviation ; 23lb; ; a) Wh - Z score transformation
The annual salary of an entry-level statistics major (in thousands of dollars) is normally distributed with a mean of 75 and a standard deviation of 12. X ∼ N ( μ = 75, σ = 12 ). What minimum salary should a statistics major aim for to earn amongst the to - Two sigma
Khail took his math test and scored 88. If the class average was 78 with a standard deviation of 5, what percent of students earned a higher grade than Khail's grade? - 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?
- 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 - Significance 61784 Determine the interval estimate of the standard deviation of the meantime to find a parking space. We found out from a survey of 200 residents that the average time is one hour and 25 minutes, and the standard deviation is 15 minutes. Use a 1% significanc
- 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 - 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
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%Do you have homework that you need help solving? Ask a question, and we will try to solve it. Solving math problems.
