In: Statistics and Probability
A particular fruit's weights are normally distributed, with a
mean of 515 grams and a standard deviation of 28 grams.
If you pick 4 fruit at random, what is the probability that their
mean weight will be between 470 grams and 557 grams (Give answer to
4 decimal places.)
Solution :
Given that ,
mean =  
= 515
standard deviation = 
 = 28
n = 4

= 515

=
  /
n= 28 / 
 4=14
P(470<  
   <
557) = P[(470-515) / 14< (
-
) /  
 < (557-515) / 14)]
= P(-3.21 < Z <3 )
= P(Z <3 ) - P(Z <- 3.21)
Using z table
=0.9987-0.0007
=0.9980
probability=0.9980