โจทย์ความน่าจะเป็น มหา'ลัย ปี 1 ครับ
 

It has been estimated that the odds of being struck by lightning in a given year are 1 of 240,000.Using this information for:
a. Express the odds in terms of "odds against"
b. What is the probability that a randomly selected individual will be struck by lightning this year?
c. What is the probability that the person in part (b) will be struck by lightning at least once during the next 20 years?
ขอบคุณครับ...

a. odd = 1-$e^n$
b. log 2^n/240000
c, log 2^20/240000 = 0.64039 โดยประมาณ