Brain Teasers
I See Three
Probability
Probability puzzles require you to weigh all the possibilities and pick the most likely outcome.Probability
You and 3 other people are in 4 smaller rooms which all connect to a larger room. A spinner with the numbers 1-4 is spun and that many people will enter the room. The people who will enter the room are randomly decided. What is the probability that on your first visit to the big room everyone will be there?
Hint
It's greater than 1/4.Answer
2/5thsExplanation:
All spinner options are equally likely, but you only have a 1/4th chance of being selected if it lands on 1, a 2/4th chance on 2, a 3/4th chance on 3, & a 4/4ths chance on 4.
If we get rid of the denominator we are left with 1 chance for 1, 2 chances for 2, ect.
Therefore, we have 4 chances for 4 and there are 10 (1+2+3+4) chances total, so you have a 4/10th (2/5th) chance to meet with everyone on your first visit.
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Comments
I wonder if the wording could be clarified a little? I read it as meaning that once people went to the room they stayed there, but I see the meaning is that they go back each time. The reference to the "first visit" should have made me realize my original reading was wrong, but it can help us Bears Of Very Little Brain to be explicit!
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