SOLUTION: A box contains 50 razor blades, five of these are known to be used, the remainder unused. What is the probability that exactly 3 will be used.

Algebra ->  Proportions -> SOLUTION: A box contains 50 razor blades, five of these are known to be used, the remainder unused. What is the probability that exactly 3 will be used.       Log On


   



Question 247538: A box contains 50 razor blades, five of these are known to be used, the remainder unused. What is the probability that exactly 3 will be used.

Answer by Edwin McCravy(20081) About Me  (Show Source):
You can put this solution on YOUR website!
A box contains 50 razor blades, five of these are known to be used, the remainder unused. What is the probability that exactly 3 will be used.

The numerator is the number of successful ways, which is the
number of ways to select exactly 3 from the 5 used.
That's "5 choose 3"

or 5C3 = %285%2A4%2A3%29%2F%283%2A2%2A1%29=+60%2F6=10

The denominator is the number of possible ways, which is the
number of ways to select exactly 3 from the total 50.
That's "50 choose 3"

or 50C3 = %2850%2A49%2A48%29%2F%283%2A2%2A1%29=+117600%2F6=19600

So the desired probability is

10%2F19600=1%2F1960

Edwin