14.a Statistics

Question 1

What is the “average” formula?

Answer 1

sum of terms / number of terms

Question 2

Set up the equation:

Answer 2

Question 3

Set up the equation:

Answer 3

Question 4

You can sum averages of different groups to get an _______ of the ________

Answer 4

You can sum averages of different groups to get an AVERAGE of the TOTAL

Question 5

Solve:

Answer 5

Question 6

In evenly spaced sets the number in the set increase, or decrease by _______________, and therefore share a _____________

Answer 6

In evenly spaced sets the number in the set increase, or decrease by THE SAME AMOUNT, and therefore share a COMMON DIFFERENCE

Question 7

What is the common difference of this evenly spaced set?

[ 11, 22, 33, 44, 55 ]

Answer 7

[ 11, 22, 33, 44, 55 ]

= 11 is the common difference

Question 8

What are the two possible types of evenly spaced sets on the GMAT?

Answer 8

1. A set of consecutive integers [1, 2, 3, 4]
2. A set of consecutive multiples of a given number [2, 4, 6, 8, 10]

Question 9

What does the GMAT mean with the word “inclusive”?

Answer 9

That you also include the numbers that determine the endpoints (the first and last numbers of the set).

Question 10

How many numbers are there from 50 to 101 inclusive?

Answer 10

Highest Number - Lowest Number + 1

101 - 50 + 1 = 52

Question 11

What is the formula used to calculate the number of consecutive integers, inclusive of the first and last?

Answer 11

Highest Number - Lowest Number + 1

Question 12

If set S contains only consecutive odd numbers from 45 to 187 inclusive, how many terms are in set S?

Answer 12

Question 13

What is the formula used to calculate the total number of elements in a set that is consecutive even or odd only?

Answer 13

Question 14

What is important to remember when using this formula?

Answer 14

When solving for odd numbers, then both the smallest and largest numbers must be odd.

When solving for even numbers, then both the smallest and largest numbers should be even.

Question 15

Solve:

Answer 15

[ WATCH OUT ]

Question 16

What is the formula for counting the number of multiples in a set?

Answer 16

Question 17

Solve:

Answer 17

Question 18

How would you solve this?

Answer 18

Last Number - First Number
50 - 10
= 40

(If you also had to include Sara, it would be +1)

Question 19

How would you solve this?

Answer 19

Last Number - First Number -1
50 - 10 - 1 = 39

Question 20

How would you calculate the average of an evenly spaced set?

Answer 20

Question 21

Solve:

Answer 21

Question 22

How can you use the average and number of elements in a set to find the sum of all elements in the set?

Answer 22

Sum = Average * Number of Terms

Question 23

Solve:

Answer 23

Question 24

How would you solve a question asking you to calculate the number of multiples of two integers in a set of numbers?

Answer 24

The number of multiples of A or B = # of multiples of A + # of multiples of B - the number of multiples of LCM(A, B)

Question 25

Solve:

Answer 25

Question 26

How would you solve a question asking you to calculate the number of multiples of two integers, but NOT of both, in a set of numbers?

Answer 26

The number of multiples of A or B = # of multiples of A + # of multiples of B - 2 times the number of multiples of LCM(A, B) Same as the other formula, just removing the LCM twice

Question 27

How would you solve this?

Answer 27

The number of multiples of A or B = # of multiples of A + # of multiples of B - 2 times the number of multiples of LCM(A, B)