Question

An integer is chosen from 1 to 20. The probability that the number is divisible by 4 is
(a) 1/4
(b) 1/3
(c) 1/2
(d) 1/10

Answer 1

The probability that the number is divisible by 4 is 1/4  

Given:

• An integer is chosen from 1 to 20.

To Find:

• The probability that the number is divisible by 4

Solution:

• Probability of an event  = n(E)/n(S)  
• n(E) = number of possible outcome of event
• n(S) = number of possible sample space outcome

Step 1:

An integer is chosen from 1 to 20

S = { 1 ,2 , 3 , ... , 19 , 20}

n(S) = 20

Step 2:

Numbers divisible by 4

E = { 4 , 8 , 12 , 16 , 20}

n(E) = 5

Step 3:

Calculate the probability that the number is divisible by 4

P(E) = 5/20 = 1/4

Correct option is a) 1/4

Answer 2

Given:

Integers from 1 to 20

To find:

The probability that the number is divisible by 4

Solution:

The probability that the number is divisible by 4 is 1/4. (Option a)

We can find the solution by following the steps given below-

We know that the numbers divisible by 4 between 1 to 20 are 4, 8, 12, 16, 20.

So, the number of integers 1 to 20 which are divisible by 4=5

The number of integers between 1 and 20=20

Now, the probability can be obtained by dividing the number of integers divisible by 4 between 1 and 20 and the total number of integers between 1 and 20.

We know that the probability of getting an integer between 1 and 20 that is divisible by 4=Number of integers between 1 and 20 that are divisible by 4/ Total number of integers  between 1 and 20

On putting the values, we get

The probability that the number is divisible by 4=5/20

=1/4

Therefore, the probability that the number is divisible by 4 is 1/4.