EQ: Monday, April 15, 2024

• What is a percentile?

• What is a Normal Distribution Curve?

• How do I find the percent of a population within increments of standard deviations?

• What is the 68-95-99 Rule?

Percentile

The percentage of values lower than the value of interest over the total.

17th

Kevin Hart

1

Daniel Radcliffe

Jack Black

Tom Cruise

Mark Wahlberg

Robert Downey Jr.

Johnny Depp

Brad Pitt

Ryan Gosling

Bradley Cooper

Will Smith

Will Ferrell

Jason Segel

Vince Vaughn

2

3

4

5

6

7

8

9

10

11

12

13

14

Normal Distribution Curve

​100%
of the
Population

Normal Distribution Curve

50%

50%

Drawing a Normal Distribution

​Does not
touch the
horizontal
axis

Drawing a Normal Distribution

Concave UP

Drawing a Normal Distribution

Symmetrical

Drawing a Normal Distribution

mean
with 3 SD on each side

​Normal Distribution Curve

Shows the percentage of the population by section

​Half of 68% = 34%

​Half of 95 - 68
= (95-68)/2
= 27 / 2
= 13.5%

​Half of 99.7 - 95
= (99.7- 95)/2
= 4.7 / 2
= 2.35%

One hundred seniors took the SAT at a particular site. The mean SAT score of 500 with a standard deviation of 100.

If your score is 700, how many seniors scored lower than you?

​200 300 400 500 600 700 800

2.5 %

2.5 %

100 - 2.5 = 97.5

95%

​Cheat Sheet