On march 30, 2015, president obama had an approval rating of 47% (according to a gallup poll). suppose a sample of 100 americans is taken that same week. what is the probability that the sample proportion has between a 40% and a 50% approval rating? (use 4 or more decimal places in your computations! )

Prob = 0.6449

Step-by-step explanation:

Given that on March 30, 2015, President Obama had an approval rating of 47% (according to a Gallup Poll).

i.e. population proportion P = 0.47

Sampling proportion p follows a normal distribution with mean = p = 0.47 and

std deviation =

Probability that the sample proportion has between a 40% and a 50% approval rating

= P(0.4<p<0.5)

Convert to z score

Z score for 0.4 =

Z score for 0.5 =

P(0.4<p<0.5) = P(-1.40<z<0.60)

= 0.4192+0.2257

=0.6449

1.4

2.3

step-by-step explanation:

the formula for the constant of variation is

y= kx

divide each side by x

y/x =kx/x

y/x =k

we know a and y

1.   y/x = k

4/1 =4

check the other values to make sure they are the same

8/2 = 4   12/3 =4   and 16/4 =4  

the constant of variation is 4

2.   y/x = k

3/1 =3

check the other values to make sure they are the same

6/2 = 3   9/3 =3   and 12/4 =3  

the constant of variation is 3