Question 1193711
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A dice is a form of a tetrahedron and each spaces are marked 1,2,3,4. 
The score is the number on which the dice lands.
Find the probability that when a tetrahedron is thrown the score is 
(a) an even number;
(b) a prime number;
(c) if two tetrahedral dice {{{highlight(cross(is))}}} <U>are</U> thrown, find the probability that the sum {{{highlight(cross(on))}}} <U>of</U> the two scores is 5.
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<pre>
(a)  There are two favorable outcomes of total four possible outcomes.

     These favorable are landing 2 or 4.

     Therefore, the probability under question  (a)  is  {{{2/4}}} = {{{1/2}}} = 0.5.     <U>ANSWER</U>



(b)  There are two favorable outcomes of total four possible outcomes.

     These favorable are landing on 2 or 3 (prime numbers).

     Therefore, the probability under question  (b)  is  {{{2/4}}} = {{{1/2}}} = 0.5.     <U>ANSWER</U>



(c)  In all, there are 4*4 = 16 possible outcomes, that are the pairs (m,n),
     where m and n are integer numbers from 1 to 4, inclusive.


     Of these 16 outcomes, the favorable are four pairs (1,4), (2,3), (3,2) and (4,1).

     Thus, there are four favorable outcomes of total 16 possible outcomes.

     Therefore, the probability under question  (c)  is  {{{4/16}}} = {{{1/4}}}.     <U>ANSWER</U>
</pre>

Solved.