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# What is phi and what is T?

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1. (Original post by Kestrel_Lover_Sophie)
Hmm.. I got T=14.52 hrs

P(X>T) = 0.2
= 1 -phi (T-12)/3

phi (T-12)/3 = 0.8
(T-12)/3 = 0.84 [from normal distribution table]
T-12 = 3x0.84
T = (3x0.84)+12
= 14.52

What is phi and what is T?
2. What is T and phi?

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