# probability

1. A city had an average of 2.6 lightning storms per month. What is the probability of at least 3 lightning storms during a month?

A. 12.26%

B. 21.76 %

C. 26.40%

D. 48.16%

E. none of the above

2. If the number of miles per gallon (mpg) achieved by cars of a particular model has a mean of 25 and a standard deviation of 2, what is the probability that, for a random sample of 20 such cars, the average mpg will be less than 24? Assume population distribution is normal.

A. 0.125

B. .1443

C. .2875

D .3026

E. none of the above

https://brainmass.com/statistics/probability/statistics-poisson-and-normal-distributions-140200

#### Solution Preview

1. A city had an average of 2.6 lightning storms per month. What is the probability of at least 3 lightning storms during a month?

A. 12.26%

B. 21.76 %

C. 26.40%

D. 48.16%

E. none of the above

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The answer is D) 48.16%.

Denote by X the number of lightning storms per month. We know that X follows ...

#### Solution Summary

It provides examples of calculating the probabilities when the samples follow Poisson distribution and normal distribution, respectively.