Mcqs (estimation)

1. MCQs
(Estimation)
NADEEM UDDIN
ASSOCIATE PROFESSOR
OF STATISTICS
https://www.slideshare.net/NadeemUddin17
https://nadeemstats.wordpress.com/listofbooks/

2. 1- A soft–drink machine is regulated so that the amount of drink dispensed is
approximately normally distributed with a standard deviation equal to 1.5
deciliters. A 95% confidence interval for the mean fall drinks dispensed by this
machine if a random sample of 36 drinks had an average content of 22.5 deciliters
is
a. 25.65 68.35 b. 22.01 22.991
c. 35.65 68.35 d. 45.65 68.35
2- A sample of the 12 had a mean of 62 and a standard deviation of 10. A 95%
confidence interval for the population mean is
a. 55.65 68.35 b. 56.65 68.35
c. 57.65 68.35 d. 58.65 68.35
3- A hospital administrator wishes to estimate the mean average of babies born in his
hospital. How large a sample of birth records should be take if he wants 95%
confidence level. He also wants the estimate to be within to be ± 0.05 pound of
the true means weight.
a. 20 b. 18 c. 16 d. none

3. 4- In a random sample of 400 carpet shops, it was discovered that 136 of them sold
carpets at below the list prices recommended by the manufacturer. Calculate 90%
confidence interval for the proportion of shops that sell below the list price.
a. 0.301 p  0.379 b. 0.501 p  0.379
c. 0.601 p  0.379 d. 0.701 p  0.379
5- A physician wishes to estimate with 95% confidence the mean ‘serum cholesterol’
level of a population. He wished the estimate to be within 5 units of the true
mean. From the previous work, he has learnt that the appropriate value of σ =20.
How large a sample he should take?
a. 75 b. 61 c. 66 d.none
6- A random sample of 8 cigarettes of a certain brand has an average nicotine content
of 3.6 milligrams and standard deviation of 0.9 milligrams. A 99% confidence
interval for variance is
a. 0.2796 < σ2 < 5.7331 b. 0.4796 < σ2 < 5.7331
c. 0.3796 < σ2 < 5.7331 d. 0.5796 < σ2 < 5.7331

4. 7- The heights of a random sample of 50 college students showed a mean of 174.5
centimeters and a standard deviation of 6.9 centimeters. What can we assert with
98% confidence about the possible size of our error if the estimate the mean
height of all college students to be 174.5?
a. 7.5 b. 6.1 c. 2.72 d.3.25
8- For a sample of size 20 taken from a normally distributed population with
standard deviation equal to 5, a 90% confidence interval for the population mean
would require the use of:
a. t = 1.328 b. t = 1.729
c. t = 2.12 d. z = 1.645
9- Suppose that 200 members of a group were asked whether they like a particular
product. Fifty said yes, 150 said no. assuming “yes” means a success, which of
the fallowing is correct?
a. 𝑃 = 0.33 b. p = 0.25
c. p = 0.33 d. p = 0.25

5. 10- Assume that you take a sample and calculate X bar as 100. You then calculate the
upper limit of a 90 percent confidence interval for µ; its value is 112. What is the
lower limit of this confidence interval?
a.88 b.92 c. 100 d. None
11- Which of the following is a necessary condition for using a ‘t’distribution table?
a) n is small b) s is known but σ is not.
c) the population is infinite d) (a) and (b) but not (c)
12- Which of the following is a difference between z tables and t tables?
a) The t table has values only for few percentages
b) The t table measures the chances that the population parameter we are
estimating will be in our confidence interval
c) We must specify the degrees of freedom with which we are dealing when
using a z table
d) All of these

6. 13- The average height of the 25 students in Mr. Hamza’s tenth grade math’s class is
known to be 66”. In constructing a 95 percent confidence interval for the
average height of all tenth graders, we would use:
a) The normal distribution with 24 degrees of freedom
b) The t distribution with 24 degrees of freedom
c) The t distribution with 65 degrees of freedom
d) The t distribution with 25 degrees of freedom
14- On the basis of the results obtained from a random sample of 100 women from
the district, the 95 % confidence interval for µ was calculated and found to be
(177.22 cm, 179.18cm), what would be the value of the sample mean?
a. 178.2 b. 278.2 c. 378.2 d.478.2
15- On the basis of the results obtained from a random sample of 100 women from
the district, the 95 % confidence interval for µ was calculated and found to be
( 177.22 cm, 179.18cm), what would be the value of the σ?
a. 10 b. 5 c. 7.5 d. None

7. 1-b 5-b 9-b 13-b
2-a 6-a 10-a 14-a
3-c 7-c 11-d 15-b
4-a 8-d 12-a
Answers