For quantity 50, the Z scores are ...
(50 -51.6)/1.3 ≈ -1.23 . . . . . . .company G
(50 -52.5)/1.8 ≈ -1.39 . . . . . . company H
Since the z-score from Company G is closer to zero than the z-score of Company H, the company that produced a package with 50 key rings in it is most likely Company G.
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The probability of exactly 50 key rings is higher the closer the z-score is to zero. The probability of at least 50 key rings is higher for lower z-scores. The way the problem's answer statement is worded, it appears the probability of interest is that of having exactly 50 key rings in the package.
