What is the probability that a coffee maker will have a defective cord? Express the answer as a percentage.?

Question

Of the coffee makers sold in an appliance store, 6.0% have either a faulty switch or a defective cord, 1.5% have a faulty switch, and 0.4% have both defects. What is the probability that a coffee maker will have a defective cord? Express the answer as a percentage.

Answer 1

For any two events A and B we have:

P(A and B) = P(A) + P(B) - P(A or B)

P(cord) = P(switch AND cord) + P(switch OR cord) - P(switch)

P(cord) = 0.004 + 0.06 - 0.015

P(cord) = 0.049

Answer 2

have a faulty switch=a=1.5%

have a defective cord=b=?%

have either a faulty switch or a defective cord=aUb=6%

have both defects=a∩b=0.4%

a+b=(aUb)+(aUb)

b=(aUb)+(aUb)-b=6+0.4-1.5=4.9%

Answer 3

4.5%