Step 1:

A survey had conducted with 420,095 cell phone users.

it was found that 135 developed cancer of the brain or nervous system.

Survey says that probability of a person having cancer is 0.000340.

Find the mean.

Here number of samples n = 420095.

Probability of a person having cancer is p = 0.000340.

Since it follows binomial distribution,

Mean .

Where n is number of samples,

             p is probability of success.

142.8323

Step 2:

Find the standard deviation.

Standard deviation .

Where n is number of samples,

             p is probability of success,

             q is probability of failure.

Probability of failure q = 1 - p.

q = 1 - 0.000340

q = 0.99966.

(2)

Step 1:

CIA had analyze the frequencies of letters of the alphabet.

They had examine the 2600 characters on o page.

They found that the letter r is used at rate 6% .

Find the mean.

Here number of samples n = 2600.

Probability of letter r  is  .

Since it follows binomial distribution,

Mean .

Where n is number of samples,

             p is probability of success.

Step 2:

Find the standard deviation.

Standard deviation .

Where n is number of samples,

             p is probability of success,

             q is probability of failure.

Probability of failure q = 1 - p.

q = 1 - 0.06

q = 0.94.

(3)

Step 1:

In Harris poll  370 adults are regret getting tattoos.

Based on this poll 20%  say that they were too young to get tattos.

Find the mean.

Here number of samples n = 370.

Probability of adults who regret tattoos  is  .

Since it follows binomial distribution,

Mean .

Where n is number of samples,

             p is probability of success.

Step 2:

Find the standard deviation.

Standard deviation .

Where n is number of samples,

             p is probability of success,

             q is probability of failure.

Probability of failure q = 1 - p.

q = 1 - 0.2

q = 0.8.