Probability: Replacement & Without Replacement

  • MHB
  • Thread starter mathdad
  • Start date
  • Tags
    Probability
In summary: NOT STAT.Stat textbooks can be very dense and hard to follow. Probability is definitely not a topic you want to skimp on.You are not the only person to tell me this fact. Based on my questions/solution steps, they feel that the best choice for me is the MATH...NOT STAT.Stat textbooks can be very dense and hard to follow. Probability is definitely not a topic you want to skimp on.
  • #1
mathdad
1,283
1
Can someone please explain the probability of replacement and without replacement with one simple example for each?
 
Mathematics news on Phys.org
  • #2
RTCNTC said:
Can someone please explain the probability of replacement and without replacement with one simple example for each?

Suppose we have a standard deck of 52 cards, and we wish to compute the probability that when randomly selecting 4 cards from the deck, all 4 will be aces.

With replacement, we will always have 4 ways to draw an ace out of 52 possible draws, hence:

\(\displaystyle P(X)=\left(\frac{4}{52}\right)\left(\frac{4}{52}\right)\left(\frac{4}{52}\right)\left(\frac{4}{52}\right)=\frac{1}{13^4}\)

Without replacement, with each successive draw, we will have one less way to draw an ace and one less possible draws, hence:

\(\displaystyle P(X)=\left(\frac{4}{52}\right)\left(\frac{3}{51}\right)\left(\frac{2}{50}\right)\left(\frac{1}{49}\right)=\frac{1}{13\cdot17\cdot25\cdot49}\)
 
  • #3
The ideas are not easy to grasp.
 
  • #4
RTCNTC said:
The ideas are not easy to grasp.

Probability takes some practice, and even then it can be very difficult in certain scenarios. I find it to be one of the most challenging areas of math in which I have some kind of experience. :D

Luckily, I have grown my beard long so that I can stroke and tug on it when working probability problems. (Rofl)
 
  • #5
Probability word problems are tricky and require lots of practice. Wish I had more time on my hands.
 
  • #6
RTCNTC said:
Probability word problems are tricky and require lots of practice. Wish I had more time on my hands.

You would likely be better off getting your hands on a textbook dedicated to probability to learn the development of the elementary techniques. But, you are fortunate, there are several folks here who are quite knowledgeable in this topic and who can provide guidance if you delve into this area of study. (Yes)
 
  • #7
MarkFL said:
You would likely be better off getting your hands on a textbook dedicated to probability to learn the development of the elementary techniques. But, you are fortunate, there are several folks here who are quite knowledgeable in this topic and who can provide guidance if you delve into this area of study. (Yes)

Trust me, I will dive completely into a probability textbook in the coming months. Can you recommend a good probability textbook from amazon.com? Usually, it is not just probability alone. Most of the time, textbooks in this area of math include statistics.
 
  • #8
RTCNTC said:
Trust me, I will dive completely into a probability textbook in the coming months. Can you recommend a good probability textbook from amazon.com? Usually, it is not just probability alone. Most of the time, textbooks in this area of math include statistics.

No, I don't have a good recommendation...I would try your local library first. :D
 
  • #9
MarkFL said:
No, I don't have a good recommendation...I would try your local library first. :D

What about asking someone in this forum?
 
  • #10
RTCNTC said:
What about asking someone in this forum?

Those who are both interested in probability and who may have a recommendation will likely read this thread. While I know several people here who know a great deal about probability, I don't want to name any names because that would place undue pressure on those members. It is best to let people volunteer information free from being "called out." :D

The textbook I used as a student was "Introductory Statistics, 3rd Edition" by Weiss/Hasset, ISBN 0-201-17833-8, Copyright 1991 by Addison-Wesley Publishing Co., Inc.
 
  • #11
MarkFL said:
Those who are both interested in probability and who may have a recommendation will likely read this thread. While I know several people here who know a great deal about probability, I don't want to name any names because that would place undue pressure on those members. It is best to let people volunteer information free from being "called out." :D

The textbook I used as a student was "Introductory Statistics, 3rd Edition" by Weiss/Hasset, ISBN 0-201-17833-8, Copyright 1991 by Addison-Wesley Publishing Co., Inc.

Since I am not going to dive deep into probability right now, I will search through amazon when the time is right. I want to continue posting from the David Cohen precalculus textbook, which has over 500 questions. Good night.
 
  • #12
RTCNTC said:
Since I am not going to dive deep into probability right now, I will search through amazon when the time is right. I want to continue posting from the David Cohen precalculus textbook, which has over 500 questions. Good night.

Cohen might be a good source for problems, however, for development of the theory, there are likely much better texts dedicated to the topic...that's all I'm saying here. And you might find good texts at your local library, that you can read, gain a better understanding, then return, without putting out any cash. :D
 
  • #13
MarkFL said:
Cohen might be a good source for problems, however, for development of the theory, there are likely much better texts dedicated to the topic...that's all I'm saying here. And you might find good texts at your local library, that you can read, gain a better understanding, then return, without putting out any cash. :D

You are not the only person to tell me this fact. Based on my questions/solution steps, they feel that the best choice for me is the MATH FOR DUMMIES series, which I actually enjoy.
 

FAQ: Probability: Replacement & Without Replacement

What is the difference between replacement and without replacement in probability?

Replacement in probability means that the item being selected is being put back into the pool of possible outcomes before each selection. Without replacement means that the item is not being put back and therefore the pool of possible outcomes is decreasing with each selection.

How does replacement or without replacement affect the probability of an event?

Replacement and without replacement can affect the probability of an event because with replacement, the pool of possible outcomes remains the same for each selection, while without replacement, the pool of possible outcomes decreases with each selection. This means that the probability of certain outcomes may be higher or lower depending on whether replacement or without replacement is used.

Which method, replacement or without replacement, is more commonly used in real-world situations?

Replacement is more commonly used in real-world situations because it allows for a larger number of possible outcomes and therefore can more accurately reflect real-life scenarios. Without replacement is often used in situations where the number of possible outcomes is limited or when the pool of outcomes needs to decrease with each selection.

How do you calculate probability with replacement or without replacement?

To calculate probability with replacement, you would use the formula P(A) = n(A)/n(S), where n(A) is the number of favorable outcomes and n(S) is the total number of possible outcomes. To calculate probability without replacement, you would use the formula P(A) = n(A)/n(S-n), where n(A) is the number of favorable outcomes and n(S-n) is the total number of possible outcomes after the previous selections have been made.

In which situations would it be more appropriate to use replacement or without replacement in probability?

It would be more appropriate to use replacement in situations where the pool of possible outcomes needs to remain constant for each selection, such as in rolling a die multiple times. Without replacement would be more appropriate in situations where the pool of possible outcomes needs to decrease with each selection, such as in drawing cards from a deck without replacing them.

Back
Top