a = interest rate of first CD
b = interest rate of second CD
and again, let's say the principal invested in each is $X.
![\bf a-b=3\qquad \implies \qquad \boxed{b}=3+a~\hfill \begin{cases} \left( \frac{a}{100} \right)X=240\\\\ \left( \frac{b}{100} \right)X=360 \end{cases} \\\\[-0.35em] ~\dotfill\\\\ \left( \cfrac{a}{100} \right)X=240\implies X=\cfrac{240}{~~\frac{a}{100}~~}\implies X=\cfrac{24000}{a} \\\\\\ \left( \cfrac{b}{100} \right)X=360\implies X=\cfrac{360}{~~\frac{b}{100}~~}\implies X=\cfrac{36000}{b} \\\\[-0.35em] ~\dotfill\\\\](https://tex.z-dn.net/?f=%5Cbf%20a-b%3D3%5Cqquad%20%5Cimplies%20%5Cqquad%20%5Cboxed%7Bb%7D%3D3%2Ba~%5Chfill%20%5Cbegin%7Bcases%7D%20%5Cleft%28%20%5Cfrac%7Ba%7D%7B100%7D%20%5Cright%29X%3D240%5C%5C%5C%5C%20%5Cleft%28%20%5Cfrac%7Bb%7D%7B100%7D%20%5Cright%29X%3D360%20%5Cend%7Bcases%7D%20%5C%5C%5C%5C%5B-0.35em%5D%20~%5Cdotfill%5C%5C%5C%5C%20%5Cleft%28%20%5Ccfrac%7Ba%7D%7B100%7D%20%5Cright%29X%3D240%5Cimplies%20X%3D%5Ccfrac%7B240%7D%7B~~%5Cfrac%7Ba%7D%7B100%7D~~%7D%5Cimplies%20X%3D%5Ccfrac%7B24000%7D%7Ba%7D%20%5C%5C%5C%5C%5C%5C%20%5Cleft%28%20%5Ccfrac%7Bb%7D%7B100%7D%20%5Cright%29X%3D360%5Cimplies%20X%3D%5Ccfrac%7B360%7D%7B~~%5Cfrac%7Bb%7D%7B100%7D~~%7D%5Cimplies%20X%3D%5Ccfrac%7B36000%7D%7Bb%7D%20%5C%5C%5C%5C%5B-0.35em%5D%20~%5Cdotfill%5C%5C%5C%5C)


The number of hours spent playing video games is the independent variable and cumulative grade point average is the dependent variable.
<h3>What is an independent variable?</h3>
An independent variable simply means the variable that's changed to test the effect on the dependent variable.
Here, the number of hours spent playing video games is the independent variable and cumulative grade point average is the dependent variable.
This is because the number of hours is being used to predict cumulative grade point average.
Learn more about variables on:
brainly.com/question/25223322
#SPJ1
The answer is (2,1). 2*2=4 and 9*1=9. 9+4=13
Answer:
=0.1587 or 15.87%
So option A is correct answer so 15.87% of the invoices were paid within 15 days of receipt.
Step-by-step explanation:
In order to find the percent of the invoices paid within 5 days of receipt we have to find the value of Z first.

where:
X is the random varable which in our case is 15 days
u is the mean or average value which is 20 days
S is the standard deviation which is 5 days

Z=-1.0
We have to find Probability at Z less than -1
P(Z<-1.0) which can be written as:
=1-P(Z>1.0)
From Cumulative distribution table:
=1-(0.3413+0.5)
=0.1587 or 15.87%
So option A is correct answer so 15.87% of the invoices were paid within 15 days of receipt.