Book back answers and solution for Exercise questions - Statistical Inference: Estimation, Hypothesis Testing

**Exercise 8.2**

1. Mention
two branches of statistical inference?

2. What
is an estimator?

3. What
is an estimate?

4. What
is point estimation?

5. What is interval estimation?

6. What is confidence interval?

7. What is null hypothesis? Give an
example.

8. Define alternative hypothesis.

9. Define critical region.

10. Define critical value.

11.
Define level of significance

12. What is type I error

13. What is single tailed test.

14. A sample of 100 items, draw from a
universe with mean value 4 and S.D 3, has a mean value 63.5. Is the difference
in the mean significant?

15. A sample of 400 individuals is found
to have a mean height of 67.47 inches. Can it be reasonably regarded as a
sample from a large population with mean height of 67.39 inches and standard
deviation 1.30 inches?

16. The average score on a nationally
administered aptitude test was 76 and the corresponding standard deviation was
8. In order to evaluate a state’s education system, the scores of 100 of the
state’s students were randomly selected. These students had an average score of
72. Test at a significance level of 0.05 if there is a significant difference
between the state scores and the national scores.

17. The mean breaking strength of cables
supplied by a manufacturer is 1,800 with a standard deviation 100. By a new
technique in the manufacturing process it is claimed that the breaking strength
of the cables has increased. In order to test this claim a sample of 50 cables
is tested. It is found that the mean breaking strength is 1,850. Can you
support the claim at 0.01 level of significance.

**Answers:**

**14. |z| = 1.667 **

**15. 1.2308 **

**16. |z| = 5 **

**17. 3.536**

Tags : Problem Questions with Answer, Solution , 12th Business Maths and Statistics : Chapter 8 : Sampling Techniques and Statistical Inference

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12th Business Maths and Statistics : Chapter 8 : Sampling Techniques and Statistical Inference : Exercise 8.2: Statistical Inference | Problem Questions with Answer, Solution

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