In: Statistics and Probability
A population has a mean of 50 and a standard deviation of 5. A sample of 100 observations will be taken. The probability that the mean from that sample will be between 49 and 51 is
a)0.50
b)0.6826
c)0.8413
d)0.9544
Solution :
Given that ,
mean =
= 50
standard deviation =
= 5
n = 100
= 50
=
/
n=5 /
100=0.5
P(49< <51
) = P[(49-50) / 0.5< (
-
) /
< (51-50) /0.5 )]
= P( -2< Z <2 )
= P(Z <2 ) - P(Z <2 )
Using z table
=0.9772-0.0228
=0.9554
probability= 0.9554