Total number of marbles = 10 + 1 + 5 + 4 = 20
Number of blue marbles = 1
The probability of selecting a blue marble = Number of blue marbles / Total number of marbles
So,
Probability of selecting a blue marble = [tex] \frac{1}{20} [/tex]
Number of outcomes of tossing a coin = 2
Number of favorable outcomes = 1 (Landing tail up)
So,
Probability of landing tail up = 1/2
Since, the two events are independent, the probability of occurring of both together will be the product of probabilities of individual events, so we can write:
Probability that Dan will select a blue marble and the coin will land tails up = 1/20 x 1/2 = 1/40
So, the answer to this question is option A
