normal distribution question (1 Viewer)

[waltssillyhat]

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.

 

[alphxreturns]

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]

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.