What is the symbol for standard deviation when the data set is the population?

What is the symbol of meaning when data set is population?

If slope of a line is 4 and y-intercept made by the line is 2 then the equation of line will be __________

Correct option is  (a)
Given slope of the line (m) = 4 and y intercept of the line (c) is 2..
The general equation of slope intercept form is y=mx+c
putting m=4 and c=2 in the general equation
y=4x+2
the resultant equation will be y=4x+2

What is the slope of a line which is parallel to y-axis?

Correct option is (c).
The slope of line parallel to y axis is undefined or not defined .
The line will be vertical.

What is the slope of a line which is parallel to x-axis?

Correct option is (b).
The slope of line parallel to x axis will be 1
The line be horizontal

If slope of a line is 4 and x-intercept made by the line is 2 then the equation of line will be __________

Given
Slope(m)=4 and x intercept is 2
The general equation of slope intercept form is y=mx+c
At x intercept y=0
0=mx+c

0=4*2 +c

The slope-intercept form of the linear equation is

Correct option is (a).
The slope-intercept form of the linear equation is 

The line that passes through the middle of the plotted points is known as

Correct option is (c).
The line that passes through the middle of the plotted points called Trend line

A survey was made among students in a district and the scatter plot shows the level of reading and height for 16 students in the district. Describe the association and give a possible reason for it.

Correct option is (d)
When the level of reading is 2, heights of student is 50 inches
When the level of reading is 5, heights of student is 55 inches
When the level of reading is 7, heights of student is 60inches
When the level of reading is 6, heights of student is  45,55,60 inches respectively.
The graph shows when level of reading increases heights of students also increase , which means the garph is positive but for same level of reading there are more than one students of different heights which the association is non linear

David asked 20 people if they can buy a new product that he developed at each of several prices. The scatter plot shows how many of the 20 people said “yes” at a given price. Describe the association between price and the number of buyers.

Correct option is (a)
When David kept the price of his product $2 there were total 20 buyers
when he increased the price to $4 the number of buyers reduced to 19
when he further increase  the price to $8 the number of buyers reduced to 11
The graph is clearly depicting when the dependent variable increases the independent decreases and the change in the dependent is not constant with the change iof independent variable
and hence it shows a case of non linear association

Alexa is training for a 10K race. For each of her training runs, she recorded the distance she ran and the time she ran. She made a scatter plot of her data and drew a trend line. Use the trend line to predict how long it would take Alexa to run 4.5 miles.

The slope is undefined means

Correct option is (a)
When there is increase in dependent variable without any change in independent variable the graph shows a vertical line which means the slope of the line is undefined 

The  slope is zero means

Correct option is (a).
when slop of any equation is zero it means there is no change in dependent variable with change in independent variable hence the graph becomes a horizontal line

Which association has slope -1?

Which association has slope 1?

Which figure gives perfect linear correlation?