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Mathematics
Problem
A souvenir set is prepared by choosing 2 key chains out of 7 designs and 1 pen out of 5 colours. Without carrying out any calculation, explain why the total number of distinct souvenir sets equals
7
C
2
×
5
C
1
{}^7C_2 \times {}^5C_1
7
C
2
×
5
C
1
.
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