Binomial distribution is always a symmetrical distribution. True False True False. If events A and B are independent, then P(A or B) = P(A) + P(B). True False A sample of 25 students is obtained from a normal population with a standard deviation of 5. The students in the sample have a total score of 250 in a quiz. Then, the sampling distribution of the sample mean I is N(10,1). Ox+y is equal to ox+oy when X and Y are independent where True False Ox+y is the standard deviation of X+Y, ox is the standard deviation of X, and oy is the standard deviation of Y. True False The margin of error for a 95% confidence interval for the mean y decreases as the population standard deviation decreases. True False A study is an observational study if the investigator observes the behavior of a response variable when one or more explanatory variables are manipulated. True False Central Limit Theorem is applicable only when the sample size is large and the population distribution is bell shaped. True False The P-value for a significance test for a population mean is 0.022. The hypotheses are H, := 1 versus H : # 1. A 99% confidence interval for u covers the value 1. True False In hypothesis testing, the standardized difference between a known statistic and the assumed parameter is called the test statistic. True False If a test is significant at 5% level, the probability of H, being true is 0.05.

## Answer

(A)**False**. Binomial distribution is symmetric only for p = 0.5. i.e. probability of success is 0.5. (B)

**False**. P(A or B) = P(A) + P(B) if A and B are mutually exclusive (C)

**False**. The sampling distribution of sample mean (D)

**False.**(E)

**True.**Population standard deviation and width (margin of error) of the confidence interval are directly proportional. (F)

**False.**Such a study is called experimental studies or interventional studies. (E)

**False.**The central limit theorem is applicable for large sample size only but population distribution need not be bell-shaped. (F)

**True.**99% C.I. will cover the value 1 as long as the p-value associated with the hypothesis is greater than 0.005. (G)

**True.**Many test statistics takes this form. (H)

**False.**If the test is significant at 5% level of significance, it means that if the null hypothesis was really true, there was very little chance (less than 5%) of observing the sample we have at hand.

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If X and Y are independent, oty = 0 +0.