Anyhoo, I got this wrong: S'pose you live in a place that has a constant chance of being struck by lightning throughout the year. The strikes occur at random and every day the chance of being struck is the same, and the rate works out at one strike per month. Your house gets hit by lightning today, Saturday. What is the most likely next day for your house to be struck again? (This is not a trick question, but a purely statistical one).
Sunday, as the chance of being struck everyday is the same? Or never, if lightning doesn't strike the same spot twice?
I remember in the last Blackadder in the trenches, Baldrick kept a bullet in his pocket which he had inscribed his name on, his theory being if he had the bullet with his name on it couldn’t be used to shoot him, don’t know what that’s got to do with lightning though, just thought I’d mention it
Probability theory is considered one of the least intuitive areas of mathematics. That’s an impressive intuitive answer Jord. But why Sunday, why not Monday (if all days are equally likely)? The question is about the “next” lighting strike. So not only does it have to be hit on that day (which as you say doesn’t favour any day) but for any day (other than Sunday) it had to avoid being hit before that day (otherwise it wouldn’t be the next one). It’s harder to meet two conditions than just one. I suppose it also depend what the time is on Saturday we’re asking the question - else Saturday could be the right answer too. Here’s another one (assume boys and girls are equally likely). My friend has two children. One of them is a girl. What’s the probability that he has two girls? I have another friend with two children. The youngest one is a girl. What’s the probability that he has two girls?
I'm thick as mince when it comes to scenarios such as these, or I tend to overthink massively and end up miles from the obvious at first glance I would think the answer to yours would be 50%, but if you hadn't mentioned the existing child's gender then 33%......? I do notice the wording isn't absolutely definitive though........
Thick as mince? Seems not, because you’re right (and I don’t think it’s obvious). The answers are 1/3 and 1/2. So eldest child first we could have BB BG GB GG If we know one is a girl. There are three possibilities: BG, GB, GG. In a third of these they’re both girls. So 1/3 If we know the youngest is a girl. There are two possibilities BG, GG. In half of these they’re both girls. So 1/2. It’s not the age that differentiates them. I could just have easily said the taller one is a girl and listed the possibilities on height (or used any distinguishing attribute). Again your intuition is correct. It’s formally known as Bayes’ theorem. I’ll start calling you “rain man”. No, not because you’re a statistical genius - just because your roofing is ****. I’ll stop posting puzzles now, before this turns into the “challenge Jord” thread.
Exactly as you say. It doesn't make much statistical difference, but it makes a difference. Statistically.
Yeah, I don't think Dustin needs to lose any sleep yet. I've finally thawed out and I'm immediately faced with the sort of examples I used to bunk maths lessons from..... Still, the longer we keep the politics at bay and try to control the stroke faced smilies () the better. Bring on the mathematics!
My specialist subject is exposing pernicious liars on this forum. A lot easier than stats or politics.
Okay. This is a classic. Don’t post the answer if you’ve seen it before. It’s lunchtime and your mate goes off for sandwiches. He comes back with three paper bags. Inside one is a lovely bacon, sausage and egg sandwich. The other two contain hummus (or something equally foul). Your mate knows what’s in each bag and he lets you choose a bag. They all look the same, so you choose one at random (say bag number 1). “Good job you didn’t choose bag number 2” he laughs and shows you that bag number 2 was hummus. “Still happy with bag number 1, or do you want to change and choose bag number 3?” he asks. Do you stick with bag number 1, change to bag number 3 or doesn’t it make a difference?
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