Answer:
The rate of change is 7
Step-by-step explanation:
multiply x by 7 to get the y value
When they work together, it takes John 1/x hours and it takes Brian 1/(x+15) hours to complete 1/4 of the model.
1/x + 1/( x+15 ) = 1/4 / · x ( x+15 )
x+15 + x = x ( x+15 ) /4 / · 4
8 x + 60 = x² + 15 x
x² + 15 x - 8 x - 60 = 0
x² + 7 x - 60 = 0
x² + 12 x - 5 x - 60 = 0
x · ( x + 12 ) - 5 ·( x+ 12 ) = 0
( x + 12 ) · ( x - 5 ) =0
x = - 12 ( not accepted ) or x = 5
The time taken by Brian: 5 + 15 = 20 hours
Answer:
Y=−3x2+6x+9
Step-by-step explanation:
Answer:
a) 
b) 
c) 
Step-by-step explanation:
Part a
represent the significance level
df =15
Since is a right tailed test the critical value is given by:

And we can use the following excel code to find it: "=T.INV(0.9,15)"
Part b
represent the significance level
n=20 represent the sample size
First we need to find the degrees of freedom given by:

Since is a left tailed test the critical value is given by:

And we can use the following excel code to find it: "=T.INV(0.1,19)"
Part c
represent the significance level
n=18 represent the sample size
First we need to find the degrees of freedom given by:

The value of
and 
Since is a two tailed tailed we have two critical values is given by:

And we can use the following excel code to find it: "=T.INV(0.025,17)"
Answer:
7n = 12+ 3n
Step-by-step explanation:
The first thing to do is subtract 3n from 7n. This would get you 4n = 12. 4 times 3 equals 12, so n equals 3.
To check your answer. 21 = 12+9. sure enough it matches our answer