100 likes | 221 Views
Chapter 5: Discrete Probability Distributions. Section 5.3: The Binomial Distribution. A binomial experiment is a probability distribution That satisfies the following four requirements:. two outcomes. Each trial can have only __________________ or
E N D
Chapter 5: Discrete Probability Distributions Section 5.3: The Binomial Distribution
A binomial experiment is a probability distribution That satisfies the following four requirements: two outcomes • Each trial can have only __________________ or • outcomes that can be reduced to two outcomes.These outcomes can be considered as either _______________ or _____________. success failure
A binomial experiment is a probability distribution That satisfies the following four requirements: fixed number 2) There must be a _______________ of trials. independent • The outcomes of each trial must be ____________ • of each other remain the same 4) The probability of a success must ________________for each trial.
Symbols for the Binomial Distribution p :Numerical probability of success q :Numerical probability of failure n :number of trials X :number of successes *Note: q = 1 – p
Binomial Probability Formula In a binomial experiment, the probability of exactly X successes in n trials is: ___n!__(n-X)! X! P(X) = · pX · q(n – X) or P(X) = nCX · pX · q(n – X)
Round to the nearest thousandth EXAMPLE 1: A coin is tossed three times. Find the probabilityof getting exactly one tail. P(1 tail) = nCX · pX · q(n – X) success = tail n = 3 X (# of successes)= 1 p = 0.5 q = 0.5 P(1 tail) = 3C1 · (.5)1 · (.5)(3 – 1) 3 · 0.5 · 0.25 = 0.375
Round to the nearest thousandth EXAMPLE 2: If a student randomly guesses at five multiple-choicequestions, find the probability that the student getsexactly three correct. Each questions has 5 choices. P(3 correct) = nCX · pX · q(n – X) success = correct n = 5 X (# of successes)= 3 p = 1/5 q = 4/5 P(3 correct) = 5C3 · (1/5)3 · (4/5)(5 – 3) 10 · (0.008) · (0.64) = 0.051
Round to the nearest thousandth EXAMPLE 3: A surgical technique is performed on seven patients.You are told there is a 70% chance of success. Find the probability that the surgery is successful for: a. Exactly five patients P(5) = nCX · pX · q(n – X) success = Surgery success n = 7 X (# of successes)= 5 p = 0.7 q = 0.3 P(5) = 7C5 · (0.7)5 · (0.3)(7 – 5) 21 · (0.16807) · (0.09) = 0.318
EXAMPLE 3: A surgical technique is performed on seven patients.You are told there is a 70% chance of success. Find the probability that the surgery is successful for: b. At least five patients P(5) = 7C5 · (0.7)5 · (0.3)(7 – 5) nCX · pX · q(n – X) = 21 · (0.16807) · (0.09) = 0.318 P(6) = 7C6 · (0.7)6 · (0.3)(7 – 6) nCX · pX · q(n – X) = 7 · (0.11765) · (0.3) = 0.247 P(7) = 7C7 · (0.7)7 · (0.3)(7 – 7) nCX · pX · q(n – X) = 1 · (0.08235) · (1) = 0.082
EXAMPLE 3: A surgical technique is performed on seven patients.You are told there is a 70% chance of success. Find the probability that the surgery is successful for: b. At least five patients P(5) + P(6) + P(7) = 0.318 + 0.247 + 0.082 = 0.647