Answer:
a) 1/2
b) 9/40
Step-by-step explanation:
Given
Total number of families living in Willbrook Farms Development = 20
Number of families preparing their own federal income taxes for last year = 10
Number of families for which taxes were prepared by a local professional = 7
Number of families for which taxes were prepared by H&R Block = 3
a) Probability of selecting a family that prepared their own taxes = 10/20 = 1/2
b) The probability of selecting two families, both of which prepared their own taxes
10/20 * 9/20 = 9/40
Answer:

Step-by-step explanation:
P(tail) = 
P(2) = 
P(tail and 2 ) =
×
= 
Answer:
30%. Based on the given conditions, formulate: 12/40 Cross out the common factor: 3/10 Multiply a number.
Step-by-step explanation: