Histograms

Standard Deviation(SD) measures spread
Normal Distribution has a standard unit with avg=0 and SD=1

Multiply by any positive constant
SD,avg,med all get multiplied by that constant. The whole curve gets stretched

Add/subtract a positive constant
SD and avg get added by that value and SD remains the same. Think of it as moving the bell curve to left or right as a whole

Scatter diagram or scatter plots


Corelation coeff(r) tells us how closely two variables are related in terms of a straight line.
It is always between -1(any line with negative slope) and +1(any line with positive slope). A value of 0 means that they are really not related thru a line so it is like a cloud of data.


Add/subtract a positive constant to one or both variables
SD remains the same so r stays the same

Multiply by any positive constant to one or both variables
SU is not changing so r stays the same