Companies A, B, and C produce

20%,

20%,

and

60%,

respectively, of the major appliances sold in a certain area. In that area,

4%

of the company A appliances,

3 1/2%

of the company B appliances, and

4%

of the company C appliances need service within the first year. Suppose a defective appliance is chosen at random; find the probability that it was manufactured by Company B.