There are 8 lily pads in a pond numbered 1,2,…,8. A frog starts on lily pad 1. During the i-th second, the frog jumps from lily pad i to i+1, falling into the water with probability \frac{1}{i+1}. The probability that the frog lands safely on lily pad 8 without having fallen into the water at any point can be written as \frac{m}{n}, where m,n are positive, coprime integers. Find 100m+n.
Source: Harvard-MIT Math Tournament, Guts Round, November 2021
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fyi the latex here is off. question doesn’t make any sense
Thanks for noting this. It should be fixed now.