Dice experiment

Question

In one experiment we throw three dice.Determine the probability that at least on two of them we will get even numbers.

Answer 1

Hi Jovan,

 

One way to look at it:

 

You might try drawing a tree diagram where Even has a probability of 1/2 and Odd has a probability of 1/2.

 

Some possible outcomes {E,E,E}, {O,O,O}, {E,O,E}, etc. The probability of each of those outcomes is (1/2)(1/2)(1/2)= 1/8. If you list all possible outcomes there are actually 8 of them, so 1/8 as the probability for each outcome makes sense. Now how many outcomes have either two or three evens? EEE, EEO, EOE,OEE (OR 4 out of 8). I get a probability of 4/8 = 1/2.

Answer 2

Prob( 1  even) = 3/6 = 1/2

 

Prob( 2 evens) = 1/2*1/2 = 1/4

 

Prob( 3 evens) = 1/2*1/2*1/2 = 1/8

 

Prob  ( 2 or 3 evens) = 1/4+1/8 = 3/8