You don't calculate a and b, you estimate them. And m is usually the most likely time (estimate) not the actual time.
How do you estimate them?
That's a hard question... you need to consider the best possible scenario, and the worst. It takes practice and experience. You will likely get it wrong the first few times.
The most pessimistic (P) case when everything goes wrong The most optimistic (O) case where everything goes right The most likely (M) case given normal problems and opportunities
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你不是计算 a 和 b，而是估计它们。 m 通常是最有可能的时间（估计）而不是实际时间。
这是一个很难的问题......你需要考虑最好的情况和最坏的情况。这需要练习和经验。前几次你可能会弄错。
You don't calculate a and b, you estimate them. And m is usually the most likely time (estimate) not the actual time.
That's a hard question... you need to consider the best possible scenario, and the worst. It takes practice and experience. You will likely get it wrong the first few times.
一切都不顺利时最悲观（P）的情况
一切顺利的最乐观 (O) 情况
考虑到正常问题和机会，最可能的 (M) 情况
Pert 图公式：(O + 4M + P)/6
The most pessimistic (P) case when everything goes wrong
The most optimistic (O) case where everything goes right
The most likely (M) case given normal problems and opportunities
Pert Chart Formula: (O + 4M + P)/6