Q:

Potatoes: Suppose the weights of Farmer Carl's potatoes are normally distributed with a mean of 9 ounces and a standard deviation of 1.2 ounces. Round your answers to 4 decimal places.(a) If one potato is randomly selected, find the probability that it weighs less than 10 ounces.(b) If one potato is randomly selected, find the probability that it weighs more than 12 ounces.(c) If one potato is randomly selected, find the probability that it weighs between 10 and 12 ounces.

Accepted Solution

A:
Answer: a)  79.10 %           b) 7%                c)19.85 %Step-by-step explanation:a) Z = ( × - μ ) ÷ σ           Where  μ mean of population σ standard               deviation Z is the abscissa to give the area or probability we are looking for associated to the value 10 ounces ( × ) So:  Z = ( 10 - 9 ) ÷ 1.2  ⇒ Z = 1/1.2 ⇒   Z = 0.83  it has to be below this valueFrom Z tables we get  P [ Z ≤ 0.82 ] = 0.7910  0r  79.10 %b) Following the same procedure: We look for P [ Z > ( x - μ ) ÷   σ ]    ⇒   Z  =  ( 12 -10 ) ÷ 1.2  = 2.5From Z table we get the area under the curve from the left tail up to the point Z < 2.5 ( 2.5 not included) but we were asked for the area out of that previous so 1- 0.9930 = 0.007 is the area we are looking forSo P (b) = 0.007  or 7 %Finally between the two points above mentioned ( 10 ≤  Z  ≤ 12 ) we use the previous values (taking in consideration the limits, according to the problem statement )Z ≤ 10     Z ⇒( 10-9  ) ÷ 1.2   Z = 0.7967Z ≥ 12     Z ⇒ ( 12 - 9 ) ÷ 1.2  Z = 0.9952The interval is between these two points0.9952 - 0.7967 = 0.1985   ⇒ or 19.85 %The attached help in the understanding of the solution