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**A-Level** **Mathematics**** Question Analysis Topic: Mathematics - Central Tendency**

**Exam Question: **

Two cards are drawn simultaneously (without replacement) from a well-shuffled pack of 52 cards. Find the mean and variance of the number of red cards.

**Answer:**

For A-Level Mathematics, you should know:

As two **red** cards must be drawn from the 52 cards **without** **replacement**, the corresponding probability is:

p = 26 / 52 x 25 / 51 = 25 / 102

and q = 1 - 25 / 102 = 77 / 102

As n = 2,

**Mean = np = 2 x 25 / 102 = 50 / 102 = ****0.49**

Therefore **variance = npq = 2 x 25 / 102 x 77 / 102 = ****0.37****.**

Work hard for your A-Level Mathematics examination!

End of analysis. Great!