Let Z be a standard normal variable. Find P(Z < 0.19). a) 0.5753 b) 0.5398 c) 0.
ID: 3350421 • Letter: L
Question
Let Z be a standard normal variable. Find P(Z < 0.19).
a) 0.5753
b) 0.5398
c) 0.5793
d) 0.4247
e) 0.4602
f) None of the above.
4.
Let Z be a standard normal variable. Find P(Z > -3.11).
a) 0.9987
b) 0.9918
c) 0.0010
d) 0.9990
e) 0.9991
f) None of the above
12.
Endure All, a manufacturer of batteries claims that the lifetime of their batteries is normally distributed with a mean of 500 hours and a standard deviation of 40 hours. What is the probability that an Endure All battery selected at random will last more than 610 hours?
a) 0.0030
b) 0.9965
c) 0.0035
d) 0.0228
e) 0.9970
f) None of the above.
Explanation / Answer
1) P(z<0.19) =0.5753 (using z table)
so choice A
2) P(z>-3.11) =1-P(z<-3.11)
= 1-0.0009
=0.9991
so choice E
3) z=(x-)/
z= (610-500)/40
= 110/40
=2.75
P(x>610) =P(z>2.75)
=1-P(z<2.75)
=1-0.9970
=0.0030
so choice A
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