Smith is a weld inspector at the shipyard. He knows you're keeping track of good and substandard welds that for the afternoon shift 5% of all worlds done will be substandard is Smith checks 300 of the Seney 500 rounds completed the shift which is probably that he will find less than 20 substandard Welds

Question

Advanced Placement (AP)

Bryanna Rivera

7 May, 21:14

Smith is a weld inspector at the shipyard. He knows you're keeping track of good and substandard welds that for the afternoon shift 5% of all worlds done will be substandard is Smith checks 300 of the Seney 500 rounds completed the shift which is probably that he will find less than 20 substandard Welds

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Maya Barron · Answer 1

We are given with

5% chance that all welds will be substandard = P

500 total rounds = N

300 rounds checked = n

We asked for the probability that less than x = 20 welds will be substandard

Find the proportion

p = x / n = 25/300

Determine the standard deviation

s = √ P (1 - P) / n

s = √ 0.05 (1 - 0.05) / 300

Solve for the z-score

z = (p - P) / s

Refer to the z-score table to determine the probability