The probability that a machine produces a defective item is 0.01. Each item is check as it's produced. Assume these are independent trials and compute the probability that at least 100 items must be checked to find 1 defective item.
I let x= 100, r= 1,
99C0 * (0.01)(0.99)^99, which gives 0.003967
Wrong answer. Explain please.