SOLUTION: In a scientific study there are 7 guinea pigs, 4 of which are pregnant. If 3 are selected at random without replacement, find the probability that all are pregnant. Enter your answ

Algebra ->  Probability-and-statistics -> SOLUTION: In a scientific study there are 7 guinea pigs, 4 of which are pregnant. If 3 are selected at random without replacement, find the probability that all are pregnant. Enter your answ      Log On


   

Question 1206439: In a scientific study there are 7 guinea pigs, 4 of which are pregnant. If 3 are selected at random without replacement, find the probability that all are pregnant. Enter your answer as a fraction or a decimal rounded to decimal places
Found 2 solutions by ikleyn, greenestamps:
Answer by ikleyn(52803) About Me  (Show Source):
You can put this solution on YOUR website!
.

    P = %284%2F7%29%2A%283%2F6%29%2A%282%2F5%29 = 4%2F35 = 0.1143  (rounded).    ANSWER

Solved.

The formula is self-explanatory.



Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


Or, using another basic method for computing probabilities....

The number of ways of choosing 3 of the 7 guinea pigs is C(7,3); the number of ways of choosing 3 pregnant guinea pigs is C(4,3). The probability of choosing 3 guinea pigs that are all pregnant is

C%284%2C3%29%2FC%287%2C3%29=4%2F35