Question

about 81% of the worlds population can roll their tongue. what is the probability that in a random sample of 2,000 people, more than 1,600 of them can roll their tongue

Answer 1

This is a binomial distribution question with

n = 2000

p = 0.81

q = 1 - p = 0.18999999999999995

This binomial distribution can be approximated as Normal distribution since

np > 5 and nq > 5

Since we know that

P(x > 1600.0)=?

The z-score at x = 1600.0 is,

z = -1.14

This implies that

P(x > 1600.0) = P(z > -1.14) = 1 - 0.1271431505627983

P(x > 1600.0) = {0.8729}

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