90 POINTS
In a survey of 2035 workers, 73% reported working out 3 or more days a week. What is the margin of error? What is the interval that is likely to contain the exact percent of all people who work out 3 or more days a week?

Step-by-step explanation:

Margin of error is the critical value (t score or z score) times the standard error (standard deviation of the sample).

ME = CV × SE

Since n > 30, we can use the z score as the critical value.

Assuming 95% confidence, z = 1.960.

The standard error for a proportion is:

s = √(p (1 − p) / n)

Given p = 0.73 and n = 2035:

s = √(0.73 (1 − 0.73) / 2035)

s = 0.0098

Therefore, the margin of error is:

ME = 1.960 × 0.0098

ME = 0.019

The margin of error is 1.9%.  The interval that likely contains the true percent of all people who work out 3 or more days a week is:

73% ± 1.9%

(71.1%, 74.9%)

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional