Multiple choice The sum of first five multiples of 3 is: 45 65 75 90 Reveal answer Fill a bubble to check yourself A Correct answer Explanation 3: (a) 45[Soln: Sn = [2a + (n - 1)d]× n/2⇒ S5 = [2×3 + (5 - 1)3)]× 5/2⇒ S5 = [6 + 12] × 5/2 = 18 × 5/2 = 9 × 5 = 45