In a city in Italy, 30% of the families have a MasterCard, 20% have an American Express card

In a city in Italy, 30% of the families have a MasterCard, 20% have an American Express card, and 25% have a Visa card. Eight percent of families have both a MasterCard and an American Express card. Twelve percent have both a Visa Card and a MasterCard. Six percent have both an American Express card and a Visa card.
a.  What is the probability of selecting a family that has either a Visa card or an American Express card?
b.  If a family has a MasterCard, what is the probability that it has a Visa card?
c.  If a family has a Visa card, what is the probability it has a MasterCard?
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Question # 2
A National study has determined that people who work full time average 43.4 hours worked per week.

Assume that the number of hours worked per week for those who work full time is normally distributed. Suppose 12% of these workers work more than 48 hours. Based on this percentage, what is the standard deviation of number of hours worked per week for those workers?