Question
From a well-shuffled deck of 52 cards, two cards are
drawn one after the other without replacement. What is the probability that the first card is a red ace and the second card is black?Solution
ATQ, Number of red aces in the pack = 2 Number of black cards in the pack = 26 Since 1st  card is not put back. So, the required probability: (2 C1 /52 C1 ) * (26 C1 /51 C1 ) = (2/52) × (26/51) = 1/51
1, 7, 25, 61, ?
1595, 1083, 740, 524, 399, ?Â
What will come in place of the question mark (?) in the following series?
130, 158, 214, 298, ?, 550
42, 48, 60, 84, 132, ?
945, 1890, ?, 504, 144, 32
124, 128, ?, 135, 110, 146
9 10 36 333 ? 132825
...18, 35, 68, 117, ?, 263Â
56, 27, 14.5, 6.25, ?, 1.0625
32, 48, 72, 108, 162, ?