Math Reference

Question 1

Use average to find the sum

Answer 1

Sum = Average x Number of Terms

Question 2

Least Common Multiple

Answer 2

Prime factorization of each number

Greatest number of times each factor is used

Multiply each Prime factor the greatest number of times it appears

Question 3

Average of Consecutive Numbers

Answer 3

Average of all integers from 13 to 77 is the same as the average of 13 and 77

Question 4

Count Consecutive Numbers

Answer 4

The number of integers from A to B inclusive is B - A + 1

Question 5

Simple Interest

Answer 5

Interest = Principle x rt (rate per payment period)(number of payment periods)

Question 6

Compound Interest

Answer 6

First Balance = (Principle) x (1 + [interest rate ^ (time)(c)] / c)

c = number of times interest is compounded annually

Question 7

Combined Work Formula

Answer 7

1/r + 1/s = 1/t

r = number of hour Rebecca
s= number of hours Sam
t = number of hours together

Question 8

Permutation Problem (How many possible outcomes are there when a smaller group is drawn from larger group; order does matter)

Answer 8

nPk = n! / (n-k)!

Question 9

Combination Problem (How many possible outcomes when order does not matter)

Answer 9

nCk = n! / k!(n-k)!

Question 10

Standard Deviation

Answer 10

Find the mean

Find the difference between the mean and each value in the set

Square each of the differences

Find the average of the squared differences

Take the positive square root of the average

Question 11

Sum of Angles in a Polygon

Answer 11

(n - 2) x 180

n = number of sides

Question 12

Regular Polygon Angle Measures

Answer 12

[(n - 2) x 180] / n

Question 13

Length of an Arc

Answer 13

Length of Arc = n/360 x 2(pi)r

Question 14

Area of Sector

Answer 14

Area of Sector = n/360 x (pi)r^2