THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION:
Suppose that 20% of all invoices are for amounts greater than $800.A random sample of 50 invoices is taken.
-What is the probability that at least 25% of these 50 invoices are for more than $800?
A)0.1894
B)0.8106
C)0.3106
D)0.8894

Question

Quizplus · Accepted Answer

The probability of an invoice being for more than $800 is 0.2. The probability of an invoice being for less than or equal to $800 is 0.8. The probability of at least 25% of the 50 invoices being for more than $800 is the same as the probability of at least 13 of the 50 invoices being for more than $800. This can be calculated using the binomial distribution:P(X >= 13) = 1 - P(X < 13) = 1 - sum(binomial(50, 0.2, k) for k in range(13)) = 0.1894Therefore, the correct answer is A.