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It's kind of a poorly stated problem. It would be better if they said: 1000 people were asked the question "Is this car blue?" and 900 answered yes, what is t
by dfrey 9y ago
It's kind of a poorly stated problem. It would be better if they said:
1000 people were asked the question "Is this car blue?" and 900 answered yes, what is the probability that the car is blue.
or
1000 people were asked the question "What is the color of this car?" and 900 answered "blue", what is the probability that the car is blue.
The second question is far more likely to produce responses like "navy", "turquoise", etc that aren't exactly blue, but are very similar.
- munificent 9y agoEven that doesn't fully specify the problem since we don't know the prior probability of a random car being blue. Reword the question to be "rainbow", "chartreuse" or some other less common car color and the probability should go down.
- lisper 9y ago> we don't know the prior probability of a random car being blue That's true, but irrelevant. The problem stipulated that this car is in fact blue, so the prior in its being blue is 1.
- munificent 9y agoThe person being asked what the probability is doesn't know the fact, so the prior probability from their perspective isn't 1.