A technology company made a $5 million profit on its first $15 million in sales and a $12 million profit on its next $30 million in sales. By what percent did the ratio of profit to sales increase from the first $15 million in sales to the next $30 million in sales?  Choose the correct choice from the following options.
A) 10 %
B) 20 %
C) 30 %
D) 40 %
E) 50 %

Rationale: solution : this is a percent increase problem . we will use the formula : percent change = ( new – old ) / old x 100 to calculate the final answer . we first set up the ratios of profits to sales . the first ratio will be for the first 15 million in sales , and the second ratio will be for the next 30 million in sales . because all of the sales are in millions , we do not have to express all the trailing zeros in our ratios . first 15 million profit / sales = 5 / 15 = 1 / 3 next 30 million profit / sales = 12 / 30 = 2 / 5 we can simplify each ratio by multiplying each by the lcm of the two denominators , which is 15 . keep in mind that we are able to do this only because our answer choices are expressed in percents . first 15 million royalties / sales = ( 1 / 3 ) x 15 = 5 next 30 million royalties / sales = ( 2 / 5 ) x 15 = 6 we can plug 5 and 6 into our percent change formula : ( new – old ) / old x 100 [ ( 6 – 5 ) / 5 ] x 100 1 / 5 x 100 , so a 20 % increase . answer b .
Answer: B