What is the z-score with a confidence level of 95% when finding the margin of error for the mean of a normally distributed population from a sample?

Z is 1.96 for a confidence interval of 95%

Step-by-step explanation:

We can find the confidence level with the formula

z = X-μ/σ

X = Raw score,

μ = mean,

σ = standard deviation.

Z is 1.96 for a confidence interval of 95%

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