Question

What is the probability of either event occurring when you roll adie?Event A: Rolling a prime numberEvent B: Rolling a 4Express your answer as a simplified fraction.

Answer 1

Given:

Roll a die.

Required:

We need to find the probability of rolling a prime number and a number 4.

Explanation:

A)

A die has sic sides and is numbered from 1 to 6.

The sample space, S ={1,2,3,4,5,6}

Let A be the event of rolling a prime number.

Recall that a prime number is a whole number greater than 1 whose only factors are 1 and itself.

$A=\lbrace2,3,5\rbrace$$n(A)=3$

The probability of rolling a prime number is P(A).

$P(A)=\frac{n(A)}{n(S)}$$P(A)=\frac{3}{6}$$P(A)=\frac{1}{2}$

B)

Let B be the event of rolling a number 4.

$B=\lbrace4\rbrace$$n(B)=1$

The probability of rolling a number 4 is P(B).

$P(B)=\frac{n(B)}{n(S)}$$P(B)=\frac{1}{6}$

Final answer:

The probability of rolling a prime number is 1/2.

The probability of rolling a 4 is 1/6.