Mean + percentages - practice problems
Number of problems found: 50
- 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 student 5
A student took the measurements of his classroom and gave the width as 7m and the length as 9m. If there is an error of 2 percent in measurement, determine the greatest value of [X+Y]/X if X and Y are the width and length of the classroom, respectively. G - 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.
- Discrete and continuous
2,3,4,4,5,5,5,6,6,7 Assume the scores are measurements of a Discrete variable and find the median. Assume the scores are measurements of a continuous variable and find the median by locating the precise midpoint of the distribution. - Find median
What is the median value in this list? 6/10,1/2,0.9,75%,0.03 - 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 - Successful 83167
Eighth-grade test results: 8D =? 8B = 47 8A = 44 8E = 37 8C = 28 Class 8A achieved exactly the average result. How many points did the winning class 8D get? By what % is class 8B more successful than class 8C? - Distribute 82137
We have a profit of 40000e, and the work took 30 days. The first worker is promised 38% of the profit but only works for 15 days, the second worker is promised 33% of the profit and works for 20 days, and the third is promised 28% of the profit and works
- Throughout 82075
In the metro, trains run in one direction at the same speed and the same intervals. Yesterday, there were 24 trains throughout the day. More trains will run today, as the time interval between trains will be shorter by 20%. How many more trains will there - 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? - Score on tests
On the first six tests in his Mathematics subject, his scores were 92, 82, 86, 93, 96, and 91. If he took the seventh test and raised the mean of his scores by exactly one point, what is his score on the 7th test? - 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 is the minimum salary a statistics major should aim for in order to ear
- 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? - Construction 71794
Two different trucks together would bring the construction material in 6 hours. However, after 4 hours, the first car was transferred to another job, and the second one was driven for another 6 hours. How many hours would it take for the first car to deli - 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
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