True or False

1. Once a probability density function f(x) is identified, the probability that x takes a value between some lower value x1 and some higher value x2 can be found by computing the area under the graph of f(x) over the interval from x1 to x2.

2.The most commonly used probability distribution for describing a continuous random variable is the normal probability distribution which looks like a bell-shape.

3. 68.3 % of the values of a normal random variable are within plus or minus one standard deviation of its mean.

4.95.4 % of the values of a normal random variable are within plus or minus two standard deviation of its mean.

5.99.7 % of the values of a normal random variable are within plus or minus three standard deviation of its mean.

6.A sample is the collection of all the elements of interest.

7.A simple random sample of size n from a finite population of size N is a sample selected such that each possible sample size of n has the same probability of being selected.

8.In selecting random samples of size n from a population, the sampling distribution of the sample mean can be approximated by a normal distribution as the sample size becomes large.

9.If the expected value of the sample statistics is equal to the population parameter being estimated, the sample statistics is said to be an unbiased estimator of the population parameter.

10.The point estimator with the smaller standard error is said to have greater relative efficiency.