April 18, 2023
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!