Answer:
Variable A and variable B have a negative linear association.
Step-by-step explanation:
We are asked to find which best describes the association between variable A and variable B.
From the scatter plot we could clearly see that as the value of variable A are increasing the corresponding value of variable B is decreasing.
Also we could see that the points are linear.
Hence, the relationship that best describes variable A and variable B is:
Negative linear Association
Every confidence interval has associated z value. As confidence interval increases so do the z value associated with it.
The confidence interval can be calculated using following formula:

Where

is the mean value, z is the associated z value, s is the standard deviation and n is the number of samples.
We know that standard deviation is simply a square root of variance:

The confidence interval of 95% has associated z value of <span>1.960.
</span>Now we can calculate the confidence interval for our income:
Answer:
Part A - the independant variable is the monthly allowance, and the dependent amount is the one that he has to get As for in order to receive it.
Part B - y = 30x + 20
Step-by-step explanation:
First we need to find the probability of selecting the 1 blue marble out of the 20 marbles total, which is 1/20.
Next, we need to find the probability of tossing the fair coin so it lands tails up, which is 1/2.
To find the probability of both events happening, we need to multiply the probabilities of the two individual events:
1/20 * 1/2 = 1/40
So the answer is 1/40, or 2.5%
Sorry about the poor formatting :( I'm on my phone at the moment, which makes it difficult.
Hope I helped, and let me know if you have any questions :D