# In binomial distribution with five Bernoulli’s trials,probability of one and two success are 0.4096 and 0.2048 respectively. Find probability of success. - Mathematics and Statistics

Sum

In binomial distribution with five Bernoulli’s trials, the probability of one and two success are 0.4096 and 0.2048 respectively. Find the probability of success.

#### Solution

Given: X ~ B(n = 5, p)

The probability of X successes is

P(X = x) = "^nC_x  p^x  q^(n - x), x = 0, 1, 2,...,n

i.e. P(X = x) = "^5C_x  p^x  q^(5 - x), x = 0, 1, 2, 3, 4, 5

Probabilities of one and two successes are

P(X = 1) = "^5C_1  p^1  q^(5 - 1)

and P(X = 2) = "^5C_2  p^2  q^(5 - 2) respectively

Given: P(X = 1) = 0.4096 and P(X = 2) = 0.2048

∴ ("P"("X" = 2))/("P"("X" = 1)) = 0.2048/0.4096

i.e. (""^5C_2  p^2  q^(5 - 2))/("^5C_1  p^2  q^(5 - 1)) = 1/2

i.e. 2 xx ""^5C_2  p^2  q^3 = 1 xx ""^5C_1  "pq"^4

i.e. 2 xx (5 xx 4)/(1 xx 2) xx "p"^2 "q"^3 = 1 xx 5 xx "pq"^4

i.e. 20 "p"^2"q"^3 = 5"pq"^4

i.e. 4p = q

i.e. 4p = 1 - p

i.e. 5p = 1

∴ p = 1/5

Hence, the probability of success is 1/5.

Concept: Binomial Distribution
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#### APPEARS IN

Balbharati Mathematics and Statistics 2 (Arts and Science) 12th Standard HSC Maharashtra State Board
Chapter 8 Binomial Distribution
Miscellaneous exercise 8 | Q 17 | Page 255