A factory which produces chips in lots of ten thousand use the following scheme to check the quality of its product. From each lot of chips produced, a random sample of size 500 is taken. If the sample contains 10 or less defectives, the lot is passed. If the sample contains more than 10 defectives, another random sample of size 500 is chosen from the lot. If this sample contains 10 or less defectives, the lot is passed, otherwise, the lot is rejected. If a lot actually contains 5% defectives, find the chance that it will pass. [approximate by sampling with replacement, and use the normal curve.]