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

• A. 5/1296
• B. 5/1944
• C. 5/2592
• D. None of these

Answer 1

Answer: (C)

5/2592

Answer 2

n = Total number of ways = 6⁵

A total of 12 in 5 throw can be obtained in following two ways –

(i) One blank and four 3’s = $5C_{1}$ = 5 or

(ii) Three 2’s and two 3’s = $5C_{2} = 10$

Hence, the required probability = $\frac{15}{6^{5}} = \frac{5}{2592}$