Reasoning
By likely, we mean greater than 50% chance.
With one person there is a 0 percent chance that you'll have two people with the same birthday.
With two people the probability that they won't share a birthday is 364 / 365. The probability that they will share a birthday is therefore 1 - (364 / 365).
With three people the probability that they won't share a birthday is the same as for two people, times 363 / 365. So the probability that three people will share a birthday is 1 - (364 / 365) x (363 / 365).
Notice that with each additional person added, the probability that they shares a birthday with one of the previous persons goes up, because there are fewer "free" days remaining.
We keep adding people until the %age is greater than 50%.
Below, 10 nine-letter words have been broken into chunks of three letters.
The chunks have been moved around, no chunk is used twice, and all of the chunks are used.
Can you determine what the 10 words are?
ent sen oom ush ile cro
cla rbr ise lis ssr lig
hai mar htn age ess new
sag clo gar ion ing oth
enc ine col our erw cod
Hint
The first letters of the words are: N, C, C, C, E, H, O, C, L, M.
Answers
new + sag + ent = newsagent
cro + cod + ile = crocodile
col + lis + ion = collision
cla + ssr + oom = classroom
enc + our + age = encourage
hai + rbr + ush = hairbrush
oth + erw + ise = otherwise
clo + sen + ess = closeness
lig + htn + ing = lightning
mar + gar + ine = margarine
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