the ratio of boys to girls was 3 to 7. If there were 200 more girls than boys in 2012, how many boys were enrolled that year?

Question

How many boys were enrolled in 2012?

Answer 1

The ratio 3:7 means that 3/(3+7)=3/10=0.3 are boys and 7/(3+7)=7/10=0.7 are girls. If N= total then 0.7N-0.3N=200, so 0.4N=200 and N=200/0.4=500. Therefore, there are 0.3*500=150 boys (and 350 girls, 200 more girls than boys).

Answer 2

the ratio of boys to girls was 3 to 7. If there were 200 more girls than boys in 2012, how many boys were enrolled that year?

In any group of 10 children, 3/10 are boys, and 7/10 are girls.

In a group of 10 children, there are 4 more girls than boys.

"   "     "      "  100     "      ,    "      "   40   "       "       "      "

"   "     "      "  500     "      ,    "      "  200  "       "       "      "

So, there were 500 children enrolled in 2012.

7/10 of these children were girls, and 7/10 of 500 = 7*50 = 350

And, of course 3/10 of these children were boys, and 3/10 of 500 = 3*50 = 150.

And 350 - 150 = 200, the number of girls more than boys.

Answer: in 2012, 350 girls were enrolled.