Question #6f807

1 Answer
MattyMatty
Dec 15, 2017

#a. 0.6778#
#b. 0.0973#

Explanation:

#"P[k trains of the 10 on time] = "C(10,k) (4/5)^k (1/5)^(n-k)#

#a. C(10,8) (4/5)^8 (1/5)^2 + C(10,9) (4/5)^9 (1/5) + C(10,10) (4/5)^10#
#= 0.30199 + 0.26844 + 0.10737 = 0.6778#

#b. C(10,9) * 0.6778^9 * (1 - 0.6778) = 0.0973#

#C(n,k) = (n!)/((n-k)!k!)#

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