Question
A. According to an estimate, 50% of the people in the United States have atleast one credit card. If a random sample of 30 persons is selected, what is the probability that 19 of them has atleast one credit card?
PLIZ REALLY NEED HELP!!
THANKS VERY MUCH..
PLIZ REALLY NEED HELP!!
THANKS VERY MUCH..
Answers
Reiny
prob(having credit card ) = 1/2
prob(not having credit card ) = 1/2
I assume you want the prob that exactly 19 of the 30 people surveyed have a credit card.
If it is something like "at least 19" of the 30, it would become a rather tedious and long question.
prob(that 19 of 30 have a credit card
= C(30,19) (1/2)^19 (1/2)^11= C(30,19) (1/2)^30
= appr .05088
prob(not having credit card ) = 1/2
I assume you want the prob that exactly 19 of the 30 people surveyed have a credit card.
If it is something like "at least 19" of the 30, it would become a rather tedious and long question.
prob(that 19 of 30 have a credit card
= C(30,19) (1/2)^19 (1/2)^11= C(30,19) (1/2)^30
= appr .05088