STAT 400 Midterm: STAT400 PILACHOWSKI-T FALL2013 0101 MID SOL 1

• School: University of Maryland
• Department: Statistics and Probability
• Course: STAT 400
• Professor: All

Document Summary

Stat 400 exam 2 (4. 3 5. 4) Note: while we"d like to guarantee that this answer key is 100% correct, there may be typos we missed in the proofreading. The current enrollment in calc i is 1000 students. Verify that this situation satisfies the rule of thumb for calculating binomial probabilities using a normal approximation. The rule of thumb is that both np and nq must be greater than or equal to 10. = 700 and nq = (1000)(0. 3) = 300. Use a normal approximation to a binomial distribution to determine the probability that at most 725 of the current students earn a grade of b or better. (don"t forget the correction for continuity. ) P[x 725]; for normal approximation use continuity correction p[y < 725. 5] 1. b. (8 points) suppose x and y are random variables defined on the same sample space with the following joint probability mass function. y x. Find the marginal probability functions for x and y. y x.