A factory received a shipment of 47 hammers, and the vendor who sold the items knows there are 4 hammers in the shipment that are defective. Before the receiving foreman accepts the delivery, he samples the shipment, and if too many of the hammers in the sample are defective, he will refuse the shipment.If a sample of 4 hammers is selected, find the probability that all in the sample are defective



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