Question 588838
A $1 bill must remain in the box to have exactly $16 and the last bill taken must be the $10.
Probability that the last bill is a $1 on a random draw is 2/4=1/2
Of the 1/2 when this occurs the probability that the third bill taken is the $10 is 1/3.
1/2 * 1/3 = 1/6 the probability of winning exactly $16.
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Ed