Question

A special die is made in the shape of an icosahedron, and its faces are numbered with the numbers 1 to 20.
When the die is thrown there is an equal chance of any face landing uppermost.
If the die is thrown once, what is the probability that the face that lands uppermost has a number that is a factor of 20?

Answer 1

Factors of 20 = 20,10,5,4 2,1
Probability = no. Trials / no. Of total trials
=6/20x100=30%
Therefore there is 30% chance of getting a factor of 20

Answer 2

Given:

A dice with 20 faces, from number 1 to 20

To Find:

The probability of landing uppermost that is a factor of 20

Solution

Find the factors of 20:

20 = 1 x 20

20 = 2 x 10

20 = 4 x 5

Factors = 1, 2, 4, 5, 10, 20

There are 6 factors of 20

Find the probability of landing uppermost that is a factor of 20:

Total number of possible outcome = 20

Total number of possible that is a factor of 20 = 6

P(factors of 20) = 6/20

P(factors of 20) = 3/10

Answer: The probability is 3/10