Statistics And Probability Question 220

Question: An ordinary cube has four blank faces, one face marked 2 another marked 3. Then the probability of obtaining a total of exactly 12 in 5 throws, is

Options:

A) $ \frac{5}{1296} $

B) $ \frac{5}{1944} $

C) $ \frac{5}{2592} $

D) None of these

Show Answer

Answer:

Correct Answer: C

Solution:

  •                  $ n= $ Total number of ways  $ =6^{5} $              $ A $  total of 12 in 5 throw can be obtained in following two ways ?                    (i) One blank and four  $ 3's={}^{5}C_1=5 $                     or (ii) Three  $ 2's $  and two  $ 3's={}^{5}C_2=10 $                     Hence, the required probability  $ =\frac{15}{6^{5}}=\frac{5}{2592}. $