Answer
a. 0.318
b. 0.955
c. 0.071
d. 0.009
Work Step by Step
a. P(good and good) = $\frac{7}{12} * \frac{6}{11}$ = 0.318
b. P(at least one in three) = 1 - P(none in three)
= 1- ( $\frac{5}{12} * \frac{4}{11} * \frac{3}{10}$) = 1 - 0.045 = 0.955
c. P(good and good and good and good)
= $\frac{7}{12} * \frac{6}{11} * \frac{5}{10} * \frac{4}{9}$ = 0.071
d. P(bad and bad and bad and bad and good) = $\frac{5}{12} * \frac{4}{11} * \frac{3}{10} * \frac{2}{9} * \frac{7}{8}$ = 0.009
