Of all customers purchasing automatic garage-door openers, 75% purchase a chain-driven model. let x = the number among the next 15 purchasers who select the chain-driven model. (a) what is the pmf of x? nb(x; 15, 0.75) b(x; 15, 0.25) h(x; 3, 15, 75) b(x; 15, 0.75) h(x; 12, 15, 75) nb(x; 15, 0.25) correct: your answer is correct. (b) compute p(x > 12). (round your answer to three decimal places.) p(x > 12) = (c) compute p(9 ≤ x ≤ 12). (round your answer to three decimal places.) p(9 ≤ x ≤ 12) =

(a) b(x; 15, 0.75)

               (b) 0.197

               (c) 0.559

Step-by-step explanation:

P( X=x)=(n C x)) p^x q^(n-x)

From the question, p = 0.75

 q = 0.25

    n = 15

So, the Pmf of X implies

P( X=x)=(15C x)) 〖(0.75)〗^x 〖(0.25)〗^(15-x)

   b( x:15,0.75)

(b) p(x>12)=p(x=13)+p(x=14)+p(x=15)

=0.1169302838+0.06681730505+ 0.01336346101

=0.19711104986

≈0.197

(c) p(9≤x≤12)=p(x=9)+p(x=10)+p(x=11)+p(x=12)

  =0.09174776729+0.16514598113+ 0.22519906517                            +0.22519906517

  =0.55866049575

 ≈0.559

answer: b i think

step-by-step explanation:

9 sandwiches per hour

step-by-step explanation:

when we have a rate, we want a 1 in the denominator

27/3 = 9

27 sandwiches/ 3 hours = 9 sandwiches/hour