Thursday 24 January 2013
Assignment No.4 (Course STA301)
Spring
2012 (Total Marks 15)
Assignment 4 (Lessons 31-36)
Question
1:
Marks: 8
a. The
means and variances of the weekly incomes in rupees of two samples of workers
are given in the following table, the samples being randomly drawn from two
different factories:
|
Factory
|
Sample
Size
|
Mean
|
Variance
|
|
A
|
160
|
15.80
|
64
|
|
B
|
220
|
10.25
|
47
|
Calculate the
96% confidence interval for the real difference in the average incomes of the
workers from the two factories
b. In
a random sample of 200 persons having their lunch at the University cafeteria
on meatless day it was observed that 30 percent preferred vegetable dishes.
Find 95% confidence interval for proportion of people who preferred the
vegetable dishes.
- End -
Q1 Part B
Question
2:
Marks: 7
- A research worker wishes to estimate the
mean of a population using a sample sufficiently large that the
probability will be 0.90 that the sample mean will not differ from the
true mean by more than 30 percent of the standard deviation. How large a
sample should be taken?
- The
mean and standard deviation of the population is 30 and 5 respectively. The
probability distribution of the parent population is unknown, find the
standard deviation of the sampling distribution of
when n = 50.
Q2 Part a
