1. Scores on a certain standardized test are normally distributed with mean 509 and standard deviation 112.
A- write down the distribution of Xbar = the mean score of a SRS of 40 test takers
B- What is the probability a SRS of 40 test takers will have a mean score above 555?
C- If there is a probabily of 0.80 that a SRS of 40 test takers will have a score less than a certain number what is the score?
2. If the length of newborns are normally distributed with mean 50cm and standard deviation 5cm:
A- write down the distribution of xbar= the mean of a SRS of 8 newborns
B- what is the probability a SRS of 8 newborns will have a mean length between 48 cm and 51 cm
C- if there is a probability of 0.33 that the mean length of a SRS of 8 newborns is greater than 50 cm but less than a certain amount, what is that amount?
3. The distribution of X is X~Bin (9,1/3). Find the mean and standard deviation of x