# Using Normal approximation to binomial distribution

Smith is a weld inspector at a ship yard. He knows from keeping track of good and substandard welds that 5% will be substandard. If he checks 300 of 7500 welds, what is the probability that he will find less than 20 substandard welds?

To solve the problems on the up-coming test we will use either the "normalcdf" or InvNorm" functions on the TI-84 Plus calculator.

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To solve this question, we use normal approximation to binomial distribution because the sample size which is 300 is too large if we use formula of binomial distribution to ...

#### Solution Summary

This solution solves a probability question involving the inspection of welds using normal approximation to binomial distribution.

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