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After a fortnight they are withdrawn from their field duties and given a month’s
training for executive sales. Sales executed by them in thousands of rupees before
and after the training, in the same period are listed below:
Sales Before
Training
Sales After
Training
23 24
20 19
19 21
21 18
18 20
20 22
18 20
17 20
23 23
16 20
a. Do these data indicate that the training has contributed to their performance?
b. Find the 95 per cent confidence Interval of the training
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 sample standard deviation of the usage was 81kWh. Assuming the
that the usage is normally distributed, provide an expression for calculating a 95%
confidence interval for the mean usage in the March quarter of 2006.
Suppose x is a normal random variable with mean 60 and standard deviation 2. A z score was calculated for a number, and the z score is 3.4. What is x
The American Red Cross says that about 25% of the population has Type B blood. A blood drive is being held at your institute. Suppose that you have selected 20 blood donors in a random way. The probability that exactly 2 of the blood donors have Type B blood is
)A normally distributed population has mean 25.6 and standard deviation 3.3
(a) Find the probability that a single randomly selected element X of the
population exceeds 30.
(b)Find the mean and standard deviation of X¯ for samples of size 9.
(C)Find the probability that the mean of a sample of size 99 drawn from this
population exceeds 30.
Distinguish between a parameter and a statistic using relevant examples
The annual salaries of employees in a large company are approximately normally distributed with a mean of $70,000 and a standard deviation of $30,000.
a) What is the probability that an employee earns a salary greater than $90,000?
Formula:
b) The company provides free Child care to the employees with kids up to 5 years of age that earn the lowest 15% of salaries. What salary does a person have to earn less than, to qualify for the free child care?
Formula:
c) A sample of 20 employees is now taken. What is the probability that the sample mean is greater than $60,000?
Formula:
Solve the problem with complete solution.
Problem:A survey was conducted to determine whether sex and age are related among
stereo shop customers. A total of 200 respondents was taken and the results are
presented below.
Age Male Female Total
Male 60 50 110
Female 80 10 90
Total 140 60 200
Instruction: Conduct a test whether sex and age of stereo shop customers are
independent at 1% level of significance.
A student knows 30 of 35 answers that should be learned for the exam. There two questions in a question card.what is the probability that student doesn't know all two answers?
.In a sample survey ,six estimates were made of the same mean.When the population mean became known ,the following errors were computed:-45,112,-89,-47,-13,26.Are these errors consistent with the hypothesis that the population of errors has a zero mean?Assume that the errors are normally distributed. *
#339914 on Dec 2023