It would go around 12 times. This is because if it goes around twice in one and a half minutes, it would go around four times in three minutes. But you want to know for 9 minutes. So, three minutes times three is nine minutes, so 4×3 = 12.
Multiples of 15 are: 15,30,45,60,75,90,105,120,135,150,165,180,195,210,225,240,255,270,285,300,315,330,345,360,375,390,405,420,435,450,465,480,495,510,525,540,555,570,585,600,615,630,645,660,675,690,705,720,735,
