The population standard deviation for the heights of dogs, in inches, in a city is 3.7 inches. if we want to be 95% confident that the sample mean is within 2 inches of the true population mean, what is the minimum sample size that can be taken?

The minimum sample size that can be taken is of 14 dogs.

Step-by-step explanation:

The formula for calculating the minimum sample size to estimate a population mean is given by:

The first step is obtaining the values we're going to use to replace in the formula.

Since we want to be 95% confident, .

Therefore we look for the critical value .

Then we calculate the variance:

And we have that:

Now we replace in the formula with the values we've just obtained:

Therefore the minimum sample size that can be taken to guarantee that the sample mean is within 2 inches of the population mean is of 14 dogs.

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