Question

A person wants to buy one fountain pen, one ball pen and one pencil from a stationery shop. If there are 10 fountain pen varieties, 12 ball pen varieties and 5 pencil varieties, in how many ways can he select these articles?

Answer 1

Number of fountain pen varieties = 10
Number of  ball pen varieties = 12
Number of pencil varieties = 5
Ways to select a fountain pen = 10
Ways to select a ball pen = 12
Ways to select a pencil = 5

Ways to select a fountain pen, a ball pen and a pencil = 10 \[\times\]12\[\times\] 5 = 600               

(Using the fundamental principle of multiplication)