Answer:
0.2115
Explanation:
probability the first lefty is the second person:
1. the first person must be right handed (1-13% = 0.87)
2. the second person must be left handed (0.13)
both must happen, so this is 0.87 * 0.13
probability the first lefty is the third person:
1. the first person must be right handed (0.87)
2. the second person must be right handed (0.87)
3. the third person must be left handed (0.13)
all must happen, so this is 0.87 * 0.87 * 0.13
either the second or third person must be left handed, so we add this to get
0.87 * 0.13 + 0.87 * 0.87 * 0.13 = 0.2115