Answer all please

1 of 50 . Why is the standard deviation of the sample means less than the population standard deviation? Q It is not less; taking a group of scores at a time introduces additional error. 0 The data is sampled twice, thereby reducing error. 0 lt is not less; smaller samples will have greater variability. Q The data is "condensed" by taking a group of scores at a time, so variability is reduced. 2 of 50 Given a bellshaped and symmetric distribution, we expect the observed value of X to be within three standard deviations of the expected value about 99.7% of the time. 0 True 0 False 3 of 50 The age of professional racecar drivers is normally distributed with a mean of 30 and a standard deviation of 6. One driver is randomly selected. What is the probability that this driver is more than 23 years old? Q .023 Q .878 Q .275 Q not enough information to