Normal distribution - practice problems - page 2 of 3
Direction: Solve each problem carefully and show your solution in each item.Number of problems found: 60
- Distribution 81063
The weight of a loaf of bread should be 900 g. Loaves whose weight differs by more than 30 g from this value must be rejected. Determine the probability that a loaf is rejected if its weight has a normal distribution N(900,40).
- 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
- Entrance exam
In a college entrance exam, the participants are rated as excellent, very good, good, and fair. Consider that the scores in the exam are normally distributed with a mean of 78 and a standard deviation of 7.5. The participants receiving the top 5% of the s
- Z score transformation
Suppose a distribution has a mean µ = 8 and standard deviation σ = 4. What is the value of x if it is z = +1.50?
- 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?
- The average 7
The average lifespan for cricket is 90 days, with a standard deviation of 13 days. If we assume that the lifespan of cricket is normally distributed, a. What is the probability a randomly selected cricket has a lifespan of fewer than 75 days? b. What is t
- An insurance
An insurance company receives, on average, two claims per week from a particular factory. Assuming that a Poisson distribution can model the number of claims, find the probability it receives. three claims in a given week, more than four claims in a given
- 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 test
The fish weights in a certain lake are normally distributed with a mean of 11 lb and a standard deviation of 6. If four fish are randomly selected, what is the probability that the mean weight will be between 8.6 and 14.6 lb? Your answer should be a decim
- Suppose 6
Suppose the life span of a revolutionary light bulb is normally distributed with a mean life span of 70 thousand hours and a standard deviation of 3 thousand hours. If a light bulb is chosen at random: a) what is the probability the life span will be with
- 10km race
Joan's finishing time for the Bolder Boulder 10 km race was 1.77 standard deviations faster than the women in her age group. 415 women ran in her age group. Assuming a normal distribution, how many women ran more quickly than Joan?
- 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
- The probability
The probability that a life bulb will have a more than 682 hours lifetime is 0.9788. The probability that a bulb will have a more than 703 hours lifetime is 0.0051. Find the probability that a bulb will last for more than 648 hours.
- 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?
- A biologist
A biologist knows that the average length of a leaf of a certain plant is 4 inches. The standard deviation of the population is 0.6 inches. A sample of 20 leaves of that type of plant given a new type of plant food had an average length of 4.2 inches. At
- An exam - normal distribution
Five thousand students take an exam with a mean of 59 and a deviation of 8. How many students will score less than 75?
- 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. )
- 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
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