Question

In confidence interval estimation, we define the level of significance as: a) 1 + confidence level I. b) confidence level-1 c) 1-confidence level d) α-1 e) 1-a If we are given a sample with ơ unknown, we should use the t-distribution unless the sample size a) 5 gb) 25 : c) 30 d) 500 e) none of these In hypothesis testing, we make a Type II error when we: a) fail to reject a true Ho b) reject a true Ho c) fail to reject a false Ho d) reject a false Ho e) none . When using the t-distribution with a sample size of 30, the degrees of freedom- a) 25 b) 26 c) 30 d) 500 e) none of these Given a sample of 49 light bulbs with a mean lifetime of 1200 hours and ơ-400, find the 99% CL a) (1088, 1312) b) (1052.8, 1347.2) c) (1102,1298) d) (1071.2, 1328.8) e) none of these

Answer 1

1. Level of significance = 1 - confidence level

2. If $\sigma$ is unknown then we can use t-distribution unless the sample size greater than or equal to 30.

3. The degrees of freedom = sample size - 1.

For n=30, degrees of freedom = 30 - 1 = 29.

Here in your question option e is correct.