Question

A glazier buys his glass from four different manufacturers - Factory A (10%), Factory B (25%), Factory C (30%) and Factory D (35%). In the past, the glazier has found that 1% of Factory A' product is cracked, 1.5% of Factory B's product is cracked, and 2% of Factory C' and Factory D's products are cracked. The glazier removes the protective covering from a sheet of glass without looking at the manufacturer's name - in other words, it's a random choice. He finds the glass is cracked. What is the probability it was made by Factory C?

Answer 1