Multiple choice The ratio of the sixth and the seventh terms of the sequence 1, 3, 6, 10, ___ $5 : 3$ $3 : 4$ $4 : 3$ $6 : 9$ Reveal answer Fill a bubble to check yourself B Correct answer Explanation The sequence is triangular numbers: 1, 3, 6, 10, 15, 21, 28 where each term increases by consecutive integers 1, 2, 3, 4, 5, 6, 7. The 6th term is 15 and 7th term is 21, so the ratio is 15:21 = 3:4 when simplified.