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In how many ways can this diagram be coloured subject to the following two conditions? (i) Each of the smaller triangle is to be painted with one of three colours: red, blue or green.(ii) No

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Question

In how many ways can this diagram be coloured subject to the following two conditions?
(i) Each of the smaller triangle is to be painted with one of three colours: red, blue or green.
(ii) No two adjacent regions have the same colour.

Sum
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Solution

These conditions are satisfied exactly when we do as follows:

First paint the central triangle in any one of the three colours.

Next paint the remaining 3 triangles, with any one of the remaining two colours.

By the fundamental principle of counting

This can be done in 3 × 2 × 2 × 2 = 24 ways.

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Chapter 7: Permutations and Combinations - Solved Examples [Page 116]

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NCERT Exemplar Mathematics [English] Class 11
Chapter 7 Permutations and Combinations
Solved Examples | Q 3 | Page 116

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