Question

75. A box contains cards numbered from 1 to 20. A card is drawn at random from the box.
Find the probability that number on the drawn card is CBSE2018-4M
O a prime number () a composite number (i) a number divisible by 3
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Answer 1

Given

• A box contains card of no 1...20
• One card is drawn at randomly

To find

1. probability that number on the drawn card a prime number
2. a composite number
3. a number divisible by 3

Solution

• Total outcome is 20 (from 1 to 20)

1).

No of event for prime no is :- 2,3,,5,7,11,13,17,19

Probability = no if event/total outcome

=>p(prime no) = 8/20

2).

No of events for composite no :-4,6,8,9,10,12,14,15,16,18,20

p =(composite no) = 11/20

3).

No of events divisible by 3 :- 3,6,9,12,15,18

p ( of no divisible by 3) = 6/20