Question

A die is rolled 20 times and the number of twos that come up is tallied. Find the probability of getting the given result.

Answer 1

Answer:

Probability (P) (k successes out of n trials) = nCk * p^k * (1-p)^(n-k), where nCk = n! / (k! * (n-k)!)

for this problem n=20, p = 1/6(probability of rolling 1 two) is approximately 0.1667

P ( of getting more that 3 two's) = 1 -P(0 two's out of 20 trials) -P(1 two out of 20 trials) -P(2 two's out of 20 trials) -P(3 two's out of 20 trials)

P ( of getting more that 3 two's) = 1 -0.026 -0.104 -0.198 -0.238 = 0.434

My answer is A