# Aptitude - Probability - Discussion

Discussion Forum : Probability - General Questions (Q.No. 1)

1.

Tickets numbered 1 to 20 are mixed up and then a ticket is drawn at random. What is the probability that the ticket drawn has a number which is a multiple of 3 or 5?

Answer: Option

Explanation:

Here, S = {1, 2, 3, 4, ...., 19, 20}.

Let E = event of getting a multiple of 3 or 5 = {3, 6 , 9, 12, 15, 18, 5, 10, 20}.

P(E) = | n(E) |
= | 9 | . |

n(S) |
20 |

Discussion:

106 comments Page 3 of 11.
Sagaana said:
6 years ago

How to solve the same problem when the 1000 tickets mixed in the pack what is the probability of getting multiples of 3 and 5?

V S Abhirame said:
6 years ago

@Souravbaidya.

Circular board of i feet has area Pi. The area of the region containing all points which are closed to center than to periphery will be Pi/4. Hence the proportion to hit near the center is 1/4=.25. So, D is the correct answer.

Circular board of i feet has area Pi. The area of the region containing all points which are closed to center than to periphery will be Pi/4. Hence the proportion to hit near the center is 1/4=.25. So, D is the correct answer.

Siva said:
6 years ago

How come 4/20 & 6/20?

Asiya said:
6 years ago

My answer is 8/20 because in question it is stated that we take multiple of 3 or 5 not multiple of both so we should neglect 15 because it is the multiple of 3 and 5.

Anyone please help me to get it.

Anyone please help me to get it.

Deepika Balaji said:
6 years ago

Can anyone help me in solving this problem. What is the probability of getting at least one six in a single throw of three unbiased dice?

Azoya said:
6 years ago

Multiple of 3 = {3,6,9,12,15,18},

Multiple of 5 ={5,10,15},

Multiple of both 3 and 5 = {15},

So p(3) = 6/20,

p(5) = 3/20,

p(3 and 5) = 1/20.

So, answer is = 6/20 + 3/20 -1/20.

i,e. 8/20 which is 2/5 according to options.

I am getting this answer because the question is multiple of 3 or 5 . So we need to exclude multiple of 3 and 5.

Multiple of 5 ={5,10,15},

Multiple of both 3 and 5 = {15},

So p(3) = 6/20,

p(5) = 3/20,

p(3 and 5) = 1/20.

So, answer is = 6/20 + 3/20 -1/20.

i,e. 8/20 which is 2/5 according to options.

I am getting this answer because the question is multiple of 3 or 5 . So we need to exclude multiple of 3 and 5.

Anonymous said:
6 years ago

Why didnt we apply the (not A) formula?

i.e. (Not blue ball) = 1 - (blue ball).

= 1 - 2/7.

= 5/7.

i.e. (Not blue ball) = 1 - (blue ball).

= 1 - 2/7.

= 5/7.

Goutam said:
7 years ago

9/20 is correct answer.

5 multiplies are 5,10,15,20.

3 multiplies are 3,9,12,15,18.

Answer = 9/20.

5 multiplies are 5,10,15,20.

3 multiplies are 3,9,12,15,18.

Answer = 9/20.

Thrideep said:
7 years ago

I think The answer is 3/4.

Naina said:
7 years ago

A coin is tossed live times. What is the probability that there is at the least one tail?

Can anyone help me with this question?

Can anyone help me with this question?

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