Probability Question 167
Question: A box contains tickets numbered from 1 to 20. Three tickets are drawn from the box with replacement. The probability that the largest number on the tickets is 7 is
Options:
A) 2/19
B) 7/20
C) $ 1-{{(7/20)}^{3}} $
D) none of these
Show Answer
Answer:
Correct Answer: D
Solution:
Let X denote the largest number on the 3 tickets drawn.
Then, $ P(X\le 7)={{(7/20)}^{3}} $ and $ P(X\le 6)={{(6/20)}^{3}}. $
Then, the required probability is $ P(X=7)={{( \frac{7}{20} )}^{3}}-{{( \frac{6}{20} )}^{3}} $
BETA
