Answer:
The coefficient of correlation=0.5
Step-by-step explanation:
We are given that
Covariance between the variable x and y=18
Variance of x=16
Variance of y=81
We have to find the coefficient of correlation
We know that
Coefficient of correlation

Using the formula



Hence, the coefficient of correlation=0.5
Answer:
A. 27°
Step-by-step explanation:
Given that s is perpendicular to r, and <1 = 3x, <2 = 5x + 18, therefore:
m<1 + m<2 = 90°
3x + (5x + 18) = 90°
Solve for x using this equation
3x + 5x + 18 = 90
8x + 18 = 90
Subtract 18 from both sides
8x + 18 - 18 = 90 - 18
8x = 72
Divide both sides by 8
x = 9
Find m<1
m<1 = 3x
Plug in the value of x
m<1 = 3(9) = 27°
Answer:
There are 392 students in the seventh grade.
Step-by-step explanation:
Let us assume that there are x number of students in the seventh grade.
Now, 3/8 of the seventh grade students were taking Advanced math at the beginning of the year, but seven dropped out by the end of the year.
So, after the end of the year there were
number of students taking advanced math.
So, as per given condition, 
⇒ 
⇒ x = 392
Therefore, there are 392 students in the seventh grade. (Answer)