We have a normal distribution, μ=50,σ=10,n=16.
Let's convert it to the standard normal distribution.
zˉ=σ/nxˉ−μ.
a) zˉ1=10/1660−50=4,P(Xˉ>60)==P(Zˉ>4)==1−P(Zˉ<4)==1−1=0 (from z-table).
b) zˉ2=10/1645−50=−2,P(Xˉ<45)==P(Zˉ<−2)==0.0228 (from z-table).
c) P(45<Xˉ<60)==P(−2<Zˉ<4)==P(Zˉ<4)−P(Zˉ<−2)==1−0.0228=0.9772.
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