Question 815715
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Hi,
According to a survey, 
college students make an average of 11 calls per day on their mobile phone.
(i) P ( x > 12)= 0.31130334853593
(ii) P(x < 11) = 0.459888702693687
(iii) P( x > 15)= 0.092603908284245
Poisson Probability Distribution
P(x; A) ={{{ (e^(-A)) (A^x) / x! }}} 
| A the average number of successes given 
http://stattrek.com/online-calculator/poisson.aspx