In how many different ways can a president vice-president and secretary be elected from a class of 15 students

2730



Explanation:

A shortcut way is to start at 15 and count down til you reach three values. So that means you'll have 15, 14, 13 which multiplies out to...

15*14*13 = 2730

Or you can use the nPr formula, with n = 15 and r = 2, to get the same answer

nPr = (n!)/((n-r)!)
15P3 = (15!)/((15-3)!)
15P3 = (15!)/(12!)
15P3 = (15*14*13*12!)/(12!)
15P3 = 15*14*13
15P3 = 2730