Answer:
Confidence interval is 128±2.326 days (between 125.674 days and 130.326 days) in 90% confidence level
Step-by-step explanation:
Confidence interval can be calculated as M±ME where
- M is the average pregnancy days of smoking women and
- ME is the margin of error in 90% confidence level.
Margin of Error in 90% confidence level can be calculated using the formula:
ME=
where
- z is the z-value in 90% confidence level (1.645)
- s is the standard deviation of pregnancy length (16)
- N is the sample size (128)
putting these numbers in the formula, we get:
ME=
=2.326
then confidence interval is 128±2.326 ( between 125.674 and 130.326 ) in 90% confidence level
Answer:
The equation not represent a proportional relationship because the line don't passes through the origin
Step-by-step explanation:
we know that
A relationship between two variables, x, and y, represent a proportional variation if it can be expressed in the form
or
In a proportional relationship the constant of proportionality k is equal to the slope m of the line <u><em>and the line passes through the origin</em></u>
so
In this problem we have

This is the equation of the line in slope intercept form
where
the slope is m=5
the y-intercept is b=5
Remember that in a proportional relationship the value of b must be equal to zero (because the line passes through the origin)
therefore
The equation not represent a proportional relationship because the line don't passes through the origin
y-intercept is -3 so it must pass the vertical line -3.
Now start from point (0,-3) and rise up by 3, then go right by 1 since the slope is 3/1 or 3.
It should look like this:
If x-7 =0
Then x =7
Substitute x=7 into f(x):
2(7)^2 - 11(7) + k
= (98-77)+k
= 21+k
Therefore k=-21 because 21+(-21)=0