Graduate Management Admission Test (GMAT)

Descriptive Statistics

Basics: mean, median, mode, frequency distribution, standard deviation, and range.

Mean: all numbers in the set added together and divided by the total of numbers in the set. Commonly known as the average.

Median: the mid point in the set of numbers.

Mode: the number that occurs most frequently.

Frequency distribution: when the numbers in the set are written in table form along with the number of times that they occur.

Standard deviation: a measure of how widely the data is dispersed from the mean.

Range: the 'spread' of the data from the lowest to the highest. For example the spread of the set 2,3,4,5,6,7 is 5. (7-2)

Sets

Basics: properties of sets, intersection and union.

Set: a collection of numbers or objects.

Intersection: for 2 sets C and D, the intersection is the set of numbers found in both sets C and D – essentially this is the overlap between the 2 sets.

Union: for the same 2 sets C and D, the union is the set of all numbers found in both sets - it is one large set encompassing all numbers found in the original 2 sets.

Counting Methods

Basics: factorials, permutations and combinations.

Factorial: denoted by n! and is the product of all the integers from 1 to n. For example, 4! is 1 x 2 x 3 x 4 = 24.

Permutations: the number of different ways of ordering a set. For example, the set RST can be ordered: RST, RTS, SRT, STR, TRS, TSR.

Combinations: similar concept to permutations but the difference is that order does not matter here. So, RST and TRS would be the same combination. Therefore, there will generally be fewer combinations than permutations for a given set.

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04/30/02

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