GMAT-Stat definitions

Question 1

Factorial

Answer 1

Factorial: A factorial is a mathematical way to express multiplication. The symbolic representation of the factorial
of n, is n!, which means n(n – 1)(n – 2)…(3)(2)(1). Thus, 5! = 5 x 4 x 3 x 2 x 1. Additionally, by rule, 1! = 1 and
0! = 1.

Question 2

Arrangement

Answer 2

An arrangement describes the way things are ordered. A question that asks you to count the number
of different arrangements is one in which the order of the elements you are counting matters. ABC is a different
arrangement than BCA. Permutation is the mathematical term for this concept. However, the GMAT rarely uses
that term.

Question 3

Combination

Answer 3

A combination describes the way things are grouped. ABC is the same combination as BCA.
A question that asks you to count the number of different groups is not concerned with the order of the elements
within each group and thus order does not matter.

Question 4

Standard Deviation

Answer 4

A standard deviation is a unit of measure for the average difference from the mean of a set. It provides a reference point for the percent distribution of the elements in the set.

Question 5

Probability

Answer 5

A probability is the likelihood or chance of an event happening.