The ratio of white balls to black balls is 1:2.If 9 grey balls are added then the ratio of white:black:grey is 2:4:3.Find the number of black balls.
Choose the correct answer
A) 11 B) 12 C) 13 D) 15 E) 16
If 9 grey balls added means, ratio of grey = 3 in all (i.e., 9/3 = 3)   Therefore, black balls = 3 *4= 
<gadget id="calculator">3 *4</gadget>
<output>12</output>
12   and the White balls= 3 *2= 
<gadget id="calculator">3 *2</gadget>
<output>6</output>
6   i.e., White= 6 ; 12lack = 12 ; Grey = 9   ANSWER:12
<result>B</result>
The ratio of white balls to black balls is 1:2.If 9 grey balls are added then the ratio of white:black:grey is 2:4:3.Find the number of black balls.