Unit 1b

multiply outcomes of events to get a total

evant a = x, event b = y, event c = z;

x*y*z*...

number of ways we can arrrange something (order matters)

nPr

n!/(n-r)!

1

+positions, places, first, second, third, prez, vice, prez, gold silver, broze

number of ways we can group something (order no matter)

nCr

n!/(r!)(n-r)!

groups,committe,

p(A) * p(b)

p(a) + p (b)

p(a) + p(b) - p(a n b)

1

the average value / mean

Sum of x (P(X=x) (number of times x is happening multiplied by the probablility of X happening)

aE(x)

E(x)+b

AE(x)+b

E(x^2)-[E(x)]^2

and

Sum of (x^2) * P(X=x) - [E(x)]^2

measure of spread of data

sqrt Variance

a^2*Var(x)

Var(x)

a^2*Var(x)

0

nCx (p)^x (1-p)^n-x

np

np(1-p)

exact prob

less than or equal to

inv norm

normal cdf