# Week 18 Doubt - Same Distribution

Apologies if it’s a stupid question.

What does it actually mean when we say

### “ all of these data points come from the same distribution”

Hi @sagar_agrawal,
It means that we’re sampling data points from a single distribution. But you might be asking something else… can you please point out the specific video and timeframe?

In week 18 “Estimate Population parameters”. Sir showed a pmf for P(King - Diamonds) and said that the P(True) = 13/52. I am confused over there

How’s P(True) = 13/52?

Here is the image

Hi @sagar_agarwal

There are 52 cards in a pack. Hence, the total no. of hands will be

``````     52C13
``````

This will be the total population space.

Now, coming to P(King-Diamonds):

We have only one King of Diamonds in a pack of 52 cards. So, assuming we have already selected it. There are 12 cards remaining to be selected out of 51 cards (King-Diamonds is already used up).

Hence, for selecting 12 cards from 51 cards:

``````     51C12
``````

Now, the final answer will be:

``````    51C12 * 1C1 / 52C13
= 51! x 1 x 13! x 39! / 39! x 12! x 52!
= 13 / 52
= 1 / 4``````
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