Question

1. True or false? Why?

1. The bigger the sample size, the more accurate the reported average of the sample.
2. Type I error is when we accept a false null hypothesis
3. A maintained hypothesis that is considered to be true unless sufficient evidence to the contrary is obtained is called the null hypothesis

2. Dyanna is the quality control manager of a candy producing factory. She has measured the weight of 25 boxes of candies. The average of the weights of these 25 boxes is 250, and the standard deviation of them is 12. She is going to provide a label for the weights of boxes with 95% confidence. What is the range of the weights that she should report?

3. Afra has taken 200 items in a factory and found that 12 of them are defective. What is the percentage of all defective products in that factory if Afra is supposed to provide the result with 90% confidence?

4. Helen is reading a news article that 75% ± 12% of students from Acsenda find a well-paid job after they finish their studies. What sample size is used in this study?

Answer 1

a. True. The bigger the sample size, the more accurate the reported average of the sample. Since increasing sample size decreases the standard error of the sample mean. Reduction in the standard error indicates that reported average of sample is more accurate.

b.False. Type I error occurred when we reject the true null hypothesis.

c. True. We assume that the null hypothesis is true unless we have enough evidence to reject it. In a hypothesis testing problem we are in favour of rejecting the null hypothesis.

Therefore, a maintained hypothesis that is considered to be true unless sufficient evidence to the contrary is obtained is called the null hypothesis