Question

According to a 2017 Gallup survey, the percentage of individuals in the United States who are invested in the stock market by age is as shown in the following table.†

Age Range Percent of Individuals
Invested in Stock Market
18 to 29 31
30 to 49 62
50 to 64 62
65+ 54
If 2,000 individuals 18- to 29-years-old are randomly sampled, what is the expected number of 18- to 29-year-olds who invest in the stock market in this sample? What is the standard deviation of the number of 18- to 29-year-olds who invest in the stock market? (Round your answers to two decimal places.)
E(x)=
=

Answer 1

Answer: 75 people

Explanation:

1).

we have percentage of people who invested in 18-29 year category

=31%

we need

n=40 people

this is

30% of x =40

or

0.3x=40

x=40/0.3 =133.33 or 134 people

2).

in 65+ category

percentage =54%

we need

n=40

this is

54% of x =40

or

0.54x=40

or

x=40/0.54 =70.07 or 75 people