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2.Find the probability that a randomly selected senior high school student spends less than 21 hours or greater than 30 hours.
1. Find the probability that a randomly selected senior high school student spends more than 26 hours but less than 29 hours.
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A random sample of 30 households was selected as part of a study on electricity usage, and the number of kilowatt-hours (kWh) was recorded for each household in the sample for the March quarter of 2006. The average usage was found to be 375kWh. In a very large study in the March quarter of the previous year it was found that the standard deviation of the usage was 81kWh. Assuming the standard deviation is unchanged and that the usage is normally distributed provide an expression for calculating a 99% confidence interval for the
mean usage in the March quarter of 2006
a psychologist believes that it will take at least an hour for certain disturbed children to learn a task. a random sample of 30 of these children results in a mean of 50 minutes to learn the task. should the psychologist modify her belief at the 0.01 level of the population standard deviation can be assumed to be 15 minutes? solution
We know that the probability of a person becoming infected with COVID-19 (based on global data) is 30% and the probability of dying as a result of COVID-19 (globally) is 7%.
After testing more than 100,000 people in the Puerto Rico, it has been found that 89% did not test positive for COVID-19; and 4% of those infected with COVID-19 die.
Calculate the probability (INCLUDE FORMULAS) that a randomly selected person in Puerto Rico:
a. DO NOT get COVID-19
b.Get COVID-19 and don't die
c. Get infected and never get tested
d. Don't get infected and don't get tested
INCLUDE FORMULAS
A population has an average u=50 and standard deviation of ó=2.3.what is the probability that a random sample is size n=8 will have a mean between 52 and 54?
Consider a population consisting of the values (1, 3, 8), n= 2 with replacement.
- mean of sampling distribution of means
- variance of the sampling distribution of means
- standard deviation of the sampling distribution
Two sample drawn from two different populations
Mean Standard deviation Size
Sample- I 165 16 65
Sample- II 150 15 52
Test at 5% level of significance that the difference of mean is 12
A certain tutorial center has six Math tutors namely, Aubrey,
Marlyn, Louie, Tonette, Leo, and Pat. The table at the right shows the number
of hours worked by each tutor. Suppose that 3 tutors are selected at random.
Compute the standard error of the mean of the number of hours they worked. complete solution
Tutors: Aubrey 15hours, Marlyn 20hrs, Louie
10hrs, Tonette 13hrs, Leo 8hrs and Pat 15hrs. Let X be the number of hours
they've worked.
A normally distributed population has a mean of 47 and a standard deviation of 5. What is the probability that a sample of size 7 has a sample mean that is less than 44? complete solution
