SOLUTION: in a group of 21 people, seven own an ITouch phone. If 9 people are selected at random what is the probability that 5 own an ITouch

Question 190784: in a group of 21 people, seven own an ITouch phone. If 9 people are selected at random what is the probability that 5 own an ITouch
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
in a group of 21 people, seven own an ITouch phone. If 9 people are selected at random what is the probability that 5 own an ITouch
-----------------------------
# of ways to select 5 owning an ITouch: 7C5 = 7C2 = 7*6/1*2 = 21
---------------------
# of ways to select 4 not owning ITouch: 14C4 = 1001
----------------------
# of ways to select 9 without restriction: 21C9 = 293,930
-----------------------------------------------------------
Probability = [21*1001]/[293,930] = 0.07152
===================================================
Cheers,
Stan H.
RELATED QUESTIONS
In a class of 100 people, 25 own fords, 20 own dodges, 13 own toyotas, 10 own both fords... (answered by ikleyn)

Suppose that 43% of people own dogs. If you pick two people at random, what is the... (answered by Fombitz)

Suppose that 28% of people own dogs. If you pick two people at random, what is the... (answered by mathmate)

Suppose that 16% of people own dogs. If you pick two people at random, what is the... (answered by Fombitz)

Suppose that 70% of people own dogs. If you pick two people at random, what is the... (answered by ikleyn)

Suppose that 11% of people own dogs. If you pick two people at random, what is the... (answered by Boreal)

Suppose that 69% of people own dogs. If you pick two people at random, what is the... (answered by MathLover1)

Suppose that 44% of people own dogs. If you pick two people at random, what is the... (answered by ikleyn)

Suppose 67% of people own dogs. If you pick two people at random, what is the probability (answered by Edwin McCravy)