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1. A study of 40 SHS English teachers established that they spent 12.6 minutes revising a student’s term paper.
- Find the 90% confidence interval in the mean time for all composition papers when minutes.
- If the teacher affirmed that she spent an average of 30 minutes revising a term paper, what would be your reaction?
2. Find the sample size to estimate a population mean within 95% confidence if the standard deviation is 6.2.
3. The prices for LED are listed: 22 500, 24 000, 21 500, 20 200, 20 600, 21 100, 210 000, 19 300, 25 000 and 22 500. Estimate the true mean of the data set with 90% confidence level.
A bakeshop owner determines the number of boxes of pandesal that are delivered each day. Find the standard deviation of random variable X=number of boxes of pan desal that are delivered each day.
What is the proportion of the area of region between z =1 and z=
2
Suppose four cellphones are tested. Let D represent the defective cellphone and N for non defective cellphone. How many possible outcomes will occur from the experiment
The sample mean is (2,4) with sample size 2 is
Consider the population consisting of the values (4, 6, 8).
a. List down all the possible samples of size 2 with replacement.
b. Compute the mean of each sample.
c. Compute the mean of the sampling distribution of means.
d. Identify the probability of each sample.
e. Compute the population mean.
f. Compare the population mean with the mean of the sampling distribution of means.
The score of entrance examination takers who took a 600 item exam resemble a normal distribution with a mean of 220 and a standard deviations of 10. The coordinator would like to get the lowest 15% of thr scores and invite them for a retake examination. What range of scores indicates the inclusion in the retake of the exam?
A molding machine prepares a certain kind of car spare part with a target
diameter p = 42.23 mm. The machine has some variability, so the standard
deviation of the diameter is o = 0.003 mm. A sample of 10 spare parts is
inspected each hour for the process control purposes and record are kept of
the sample mean diameter. What will be the mean and standard deviation of
the number recorded?
1. The scores of the individual students on a national test have a normal
distribution with the mean 19.5 and standard deviation of 5.6. At Ramos High
School, 86 students took the test. If the scores at this school have the same
distribution as national scores, what are the mean and standard deviation of the
sample mean for 86 students?
The average number of milligrams of cholesterol in a cup of a certain
brand ice cream is 670 mg and standard deviation is 45 mg, Assume the
variable is normally distributed.
a. If a cup of ice cream is selected, what is the probability that the
cholesterol content will be more than 700 mg?
b. If a sample of 20 cups is selected what is the probability that the mean of
the sample will be larger than 700mg?
