Question

The results for a survey of 130 students who were selected randomly are listed below:

•70 students have a cell phone plan with company X
•32 students have a cell phone plan with company Y
•28 students do not have a cell phone
The total population of students was 390. Based on the data, what is the best approximation for the total number of students who have a cell phone plan with company X?

A) 210
B) 96
C) 84
D) 724

Answer 1

A) 210

Explanation:

70 students have company X, out of the sample size 130. This forms the fraction 70/130.

n students have company X, out of the population 390. The n is simply a placeholder for a number. This forms the fraction n/390

Equate the two fractions, cross multiply, then divide both sides by 130 to solve for n

Doing all that gives us the following

70/130 = n/390

70*390 = 130*n ..... cross multiply

27300 = 130n

130n = 27300

130n/130 = 27300/130 ...... divide both sides by 130

n = 210

Out of the entire population, the best approximation to the number of students who have company X is 210 people.

Answer 2

A) 210

Explanation:

The percentage of students who have a cell phone plan with company x is student with plan x over total.The total is 130

P(x) = 70/130

The number of students with cell phone company x is found by multiplying the total number of students times the percentage of students with company x

Students with company x = total * P(x)

= 390 * 70/130

= 210