The ratio of Red Balls to Blue Balls is 3:7. 70% of the Red balls and 30% of the Blue balls are tennis balls. How many of the balls are tennis balls?  Choose the correct answer:
A) 44%
B) 40%
C) 45%
D) 42%
E) 48%
let total no of Balls 100, Red Ball 30 and Blue Ball 70, so tennis ball for Red and Blue Ball respectively 30* 70/100= 
<gadget id="calculator">30* 70/100</gadget>
<output>21</output>
21 and   70* 30/100= 
<gadget id="calculator">  70* 30/100</gadget>
<output>21</output>
21   so total 42 tennis balls out of 100 balls..so required % is 42%   ANSWER:42%
<result>D</result>
The ratio of Red Balls to Blue Balls is 3:7. 70% of the Red balls and 30% of the Blue balls are tennis balls. How many of the balls are tennis balls?