A factory received a shipment of 11 capacitors, and the vendor who sold the items knows there are 4 capacitors in the shipment that are defective. Before the receiving foreman accepts the delivery, he samples the shipment, and if too many of the capacitors in the sample are defective, he will refuse the shipment. Give answer as a decimal to three decimal places.

(a) If a sample of 4 capacitors is selected, find the probability that all in the sample are defective.

(b) If a sample of 4 capacitors is selected, find the probability that none in the sample are defective.