Urn 1 contains 4 green and 5 yellow marbles. Urn 2 contains 7 green and 4 yellow marbles. An experiment consists of choosing one of two urns at random then drawing a marble from the chosen urn. Urn 1 is more likely to be chosen than Urn 2 with probability 0.63.

Required:
a. What is the probability that a green marble was chosen?
b. What is the probability that a yellow marble was chosen, if it is known that Urn 2 was chosen?
c. What is the probability that Urn 1 was chosen, if it is known that a yellow marble was drawn?

Respuesta :

Answer:

a

[tex]P(N_g) = 0.5155[/tex]

b

 [tex]P(K ) = 0.36364[/tex]

c

[tex]P(U1 | N_y ) = 0.7223[/tex]  

Step-by-step explanation:

From the question we are told that

  The number of green marbles in Urn 1 is  [tex]N_g = 4[/tex]

   The number of yellow marbles in Urn 1 is [tex]N_y = 5[/tex]

   The number of green marbles in Urn 2 is  [tex]n_g = 7[/tex]

   The number of yellow marbles in Urn 1 is [tex]n_y = 4[/tex]

    The probability of choosing Urn 1 is  [tex]P(U1) = 0.63[/tex]

    The probability of choosing Urn 2 is [tex]P(U2) = 1- 0.63 =0.37[/tex]

Generally the total marble in Urn 1 is  

     [tex]N_t = N_g +N_y[/tex]

=>  [tex]N_t = 4 + 5[/tex]

=>  [tex]N_t = 9[/tex]

Generally the total marble in Urn 2 is  

     [tex]n_t = n_g +n_y[/tex]

=>  [tex]n_t = 7+4[/tex]

=>  [tex]n_t = 11[/tex]

Generally the probability of choosing green marble is

     [tex]P(N_g) = P(U1 ) * \frac{N_g}{N_t} + [P(U2 ) * \frac{n_g}{n_t} ][/tex]

=>   [tex]P(N_g) = 0.63 * \frac{4}{9} + [0.37 * \frac{7}{11} ][/tex]

=>   [tex]P(N_g) = 0.5155[/tex]

Generally  the probability that a yellow marble was chosen, if it is known that Urn 2 was chosen is mathematically represented as

     [tex]P(K ) = \frac{n_y}{n_t}[/tex]

=>   [tex]P(K ) = \frac{4}{11}[/tex]

=>   [tex]P(K ) = 0.36364[/tex]

Generally the probability of choosing yellow marble is

     [tex]P(N_y) = P(U1 ) * \frac{N_y}{N_t} + [P(U2 ) * \frac{n_y}{n_t} ][/tex]

=>   [tex]P(N_y) = 0.63 * \frac{5}{9} + [0.37 * \frac{4}{11} ][/tex]

=>   [tex]P(N_y) = 0.4845[/tex]

Generally  the  probability that Urn 1 was chosen, if it is known that a yellow marble was drawn is mathematically represented as

     [tex]P(U1 | N_y ) = \frac{ P( U1 \ n N_y)}{P(N_y)}[/tex]

=>   [tex]P(U1 | N_y ) = \frac{0.63 * [\frac{5}{9} ] }{0.4845 }[/tex]

=>   [tex]P(U1 | N_y ) = 0.7223[/tex]