.
It is the binomial type probability distribution.
The number of trial n= 20; the probability of the success trial is , and the number of success trial k = 2.
P = = = 0.136909 = 0.137 (rounded). ANSWER
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To see many other similar solved problems, look into the lessons
- Simple and simplest probability problems on Binomial distribution
- Typical binomial distribution probability problems
in this site.