Let's count this through. The probability of the first is 1/2, the second is another 1/2, so a total of 1/4. The third, 1/2, with a total of 1/8. Continue this with the rest of the 6 boys. You now have a probability of 1/64. This is the fourth solution, or d. 0.015625.
d. 0.015625.
