Question

A={2,4,6,…,18,20} then n(A)=

Answer 1

n(A) = 10

Explanation:

The number of elements in the set of even numbers from 2 to 20 is 10.

n(A) = 10

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Additional comment

Dividing the set elements by 2 maps them to the Natural numbers 1 .. 10. This makes them easy to count.