A double sampling plan is as follows: Select a sample of 25 from a lot that is large in comparison to the sample. If no more than 1 defective item is found, the lot is accepted; if more than three defective items are found, the lot is immediately rejected. Otherwise, a second sample of 50 items is taken and the lot is accepted if the combined number of defectives does not exceed three. The lot of the first sample is 4% defective, and the probability of acceptance for the first sample is 0.7358. What is the overall probability of acceptance for the lot?

Please show me solutions. The correct answer is 0.8188.