# Boris has a coin and a number cube. The number cube is labeled 1 through 6. He flips the coin once and rolls the number cube once. What is the probability that the coin lands tails-up and the cube lands on an even number?

1
by oscarchard793

2014-11-06T13:37:56+08:00
Simple math.

Probability is equal to number of ways it can happen over number of total outcome

or

P = (n1 + n2 + n3 ...) / nTotal

So a coin has two sides so that means there only 2 possibility for that

While a cube has 6 possibility

The event will be done once.

You use the word and meaning that we should use multiplication to determine the number of total outcome

So

nTotal = 2 * 6

nTotal = 12

There are 3 even number in a cube (1, 3, and 5)

So it means we have to multiply 3 to number of ways in a coin which is 1

n1 = 3 * 1

n1 = 3

Lets now compute:

P = 3/12

P = 1/4

P = 0.25 or 25%

So it means there is a 25% probability that the coin will land tails up with an even number from the cube.

W can do this in list

-H1
-H2
-H3
-H4
-H5
-H6

Tails up(T)

-T1
-T2
-T3
-T4
-T5
-T6

A total of 12

Let's list the T with even number

-T1
-T3
-T5

We have 3

3/12 = 1/4 = 0.25 = 25%

I hope it helps.