Answer:
5
0.9990
0.0401
Step-by-step explanation:
1) Probability(diamond) = 13/52 = 1/4
Probability(not diamond) = 1 - 1/4 = 3/4
Probability of atleast one diamond = 1 - probability of no diamonds
= 1 - (¾ × ¾) = 1 - 9/16 = 7/16
Expected no. = np = 12 × 7/16
= 5.25 = 5 (nearest whole no.)
2) let X be the no. of people winning the prize.
Then X ~ B(12, 7/16)
[ X follows a Binomial Distribution with 12 trials and probability of success (winning prize) = 7/16 ]
P(atleast 1 winning) = 1 - P(X=0)
= 1 - (9/16)^12
= 0.9989966087
= 0.9990 (4 dp)
3) P(X=2) = 12C2 × (7/16)² × (9/16)^10
= 0.0400613268
= 0.0401 (4 dp)
