Question

G = {x | 6 ≤ x ≤ 11, x is a counting number}

Answer 1

Answer:

n all sorts of situations we classify objects into sets of similar objects and count them. This procedure is the most basic motivation for learning the whole numbers and learning how to add and subtract them.

Such counting quickly throws up situations that may at first seem contradictory.

‘Last June, there were 15 windy days and 20 rainy days, yet 5 days were neither windy nor rainy.’

How can this be, when June only has 30 days? A Venn diagram, and the language of sets, easily sorts this out.

Let W be the set of windy days,

and R be the set of rainy days.

Let E be the set of days in June.

Then W and R; together have size 25, so

the overlap between W and R is 10.; The Venn diagram opposite displays; the whole situation.

The purpose of this module is to introduce language for talking about sets, and some notation for setting out calculations, so that counting problems such as this can be sorted out. The Venn diagram makes the situation easy to visualise.

Answer 2

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COUNTING NUMBER

A counting number is a number which is used for counting numbers

More precisely counting numbers are non negative integers

EXAMPLES

1, 2, 3, 4, 5, 6,..........

EVALUATION

$G = \{ \: x \: : 6 \leqslant x \leqslant 11 \: , \: x \: is \: a \: counting \: number \: \}$

The above set is in Set builder form

Now the roster form / tabular form is

$G \: = \{ \: 6 \: , \: 7\: , \: 8\: , \: 9\: , \: 10\: , \: 11 \: \}$