Question

A farm categorizes its chickens into 3 classes according to the weight: small, medium, andbig. For any chicken in this farm, the distribution of the weight (denoted byW) follows a GaussianPDF with mean 3.8 lb and standard deviation 0.6 lb. The categories follow the following rule
small: W <= 3.5lb
medium: 3.5 <= 4.9lb
Large: W > 4.9lb

Required:
a. What are the probabilities that a chicken is in the classes of small, medium, and large, respectively?
b. Find c such that PW < c = 0.6.
c. Suppose that 5 chickens are selected at random. What is the probability that 3 out of the 5 will be small?

Answer 1

Answer:

A) P ( chicken is small ) = 0.3085,  P ( chicken is medium ) = 0.6621

   P (chicken is large ) = 0.0294

B) C = 3.9233

C) 0.1404

Step-by-step explanation:

A) Probabilities

i) P ( chicken is small )

 P( w ≤ 3.5 ) = Fw ( 3 .5 )

                    = F ( 3.5 - 3.8 / 0.6 )

                    = F ( -0.5 ) = 1 - F( 0.5 ) [∵ F(-x) 1 - F(x) ]

                    = 1 - 0.6915 ( from Table )

                    = 0.3085

ii) P ( chicken is medium )

  P ( 3.5 < w < 4.9 )

  P ( w < 4.9 ) - P ( w < 3.5 )

= Fw ( 4.9 ) - Fw ( 3.5 )

= F ( 4.9 - 3.8 / 0.6 ) - 0.3085

= 0.9706 - 0.3085 = 0.6621  

iii) P (chicken is large )

= P ( w > 4.9 )

= 1 - P ( w < 4.9 )

= 1 - Fw ( 4.9 ) = 1 - 0.9706 = 0.0294

B) Find c

Given:  P( w < c ) = 0.6

Fw ( c ) = 0.6

F ( c - 3.8 / 0.6 ) = 0.6

c - 3.8 / 0.6 = 0.2055 ( from table )

∴C = 3.9233

C) P ( 3 out of 5 = small )

P ( 3 of 5 = small ) = 0.1404

attached below is a detailed solution