A pet groomer has 7 animals to groom for the day (2 cats and 5 dogs). If she randomly selects 4 animals to groom before lunch, what is the probability she will finish all the cats before lunch?
Choose the correct choice from the following options
A) 3/7 B) 2/7 C) 12/13 D) 5/11 E) 4/7
Combination Probability Formula: nCr = n!/[r!(n-r)!]   Total possible, select 4 animals from 7 animals = 7C4 = 7!/[4!(7 - 4)!] = 35.   To finish all 2 cats there must be 2 dogs, select 2 dogs from 5 = 5C2 = 10.   And, select 2 cats from 2 = 2C2 = 1.   2 cats and 2 dogs = (1)(10) = 10   Probability = (number outcomes favorable)/(total number outcomes) = 10/735 = 2/7   Answer: 2/7
<result>B</result>
A pet groomer has 7 animals to groom for the day (2 cats and 5 dogs). If she randomly selects 4 animals to groom before lunch, what is the probability she will finish all the cats before lunch?