normal distribution question (2 Viewers)

waltssillyhat

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why does the worked solution for this question use P(Z > -1.64485) instead of P(Z > 1.64485)? I don't understand why they made this negative.
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alphxreturns

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bc P(Z>1.644...) isnt 0.95

Z would be negative bc weight must be greater than Z score down at the bottom and still be 0.95
 

C2H6O

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cause they wanna label the box as a weight lower than 500g, so they wanna find the z score so that 95% of values will be above it, which will be a number to the left side of the normal distribution curve which is negative.
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