You want to estimate the mean number of sentences in a magazine advertisement. How many magazines advertisements must be included in the sample if you want to be 95% confident that the sample mean is within one sentence of the population mean

Complete question:

You want to estimate the mean number of sentences in a magazineadvertisement. How many magazine advertisements must beincluded in the sample if you want to be 95% confident that thesample mean is within 1 sentence of the population mean ? (sigma =5)

96

Step-by-step explanation:

We have level of confidence = 95%

Alpha = 1-0.95

= 0.05

Alpha/2 = 0.025

Z-alpha/2 = 1.96

E = margin of error = 1

For this question the formula to derthe sample size is given as:

n = [(Za/2 x sigma)/E]²

n = (1.96 x 5/1)²

n = 9.8²

= 96.04

So 96 magazines advertisement must be included in the sample to be 95% confident.

the expected value of the random variable : 0, 1 and 2

step-by-step explanation:

or

step-by-step explanation:

we need to solve for 'x' the following equation:  

we have that:

⇒

⇒ ⇒

factorizing, we get that:

  ⇒

then, the solutions are: or

nothing extraneous has been found!