HMMT 十一月 2008 · 冲刺赛 · 第 8 题
HMMT November 2008 — Guts Round — Problem 8
题目详情
英文原题
- [ 7 ] Alice rolls two octahedral dice with the numbers 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9. What’s the probability the twodice sum to 11? 6
解析
英文解析
- [ 7 ] Alice rolls two octahedral dice with the numbers 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9. What’s the probability the twodice sum to 11?
Answer: No matter what comes up on the first die, there is exactly one number that could 1
appear on the second die to make the sum 11, because 2 can be paired with 9, 3 with 8, and so on.8
So, there is a chance of getting the correct number on the second die.1
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