SOLUTION: In a small class of 10 students, 3 did not do their homework. The professor selects half of the class to present solutions to do homework problems on the board, and records how man

Question 260162: In a small class of 10 students, 3 did not do their homework. The professor selects half of the class to present solutions to do homework problems on the board, and records how many of those selected did not do their homework.
A. give a probability distribution
b. sketch its histogram
c. find expected value
Answer by edjones(8007) (Show Source): You can put this solution on YOUR website!
nCr=combination of n things taken r at a time
.
10C5=252 the denominator for all of these
probability distribution:
all 5 did their homework 7C5/252=21/252=.0833
4 did, 1 didn't. (7C4 * 3C1)/252=35*3/252=.4167
3did, 2 didn't. (7C3 * 3C2)/252=35*3/252=.4167
2 did, 3 didn't (7C2 * 3C3)/252=21/252=.0833
Make the histogram from the above figures.
.
The expectation is that 1 or 2 of the selected 5 didn't do their homework
.
Ed
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