Suppose that a cell phone manufacturer claims that, on average, it’s cell phones last 7 years. if it’s cell phones do, in fact, last an average of 7 years, what would be the expected amount of time a sample of the company’s cell phones would last? a. 7 years
b. 3.5 years
c. 9 years
d. 2 years

a. 7 years

Explanation:

If it's a sample of something, it should remain as true to the original product as possible. There should be no difference in quality between the sample cell phone and the regular cell phone. If there was, that would defeat the purpose of it being a sample.

it's equivalent, so we can say that its equal.

let's call the denominator x and the numerador is 18 less then denominator, x - 18.

multiply

2.x = 5.(x - 18)

2x = 5x - 90

90 = 5x - 2x

90 = 3x

x = 90/3

x = 30

so: