A school has 100 students. Half of the students are girls, the other half are boys. 20% of the girls have dogs at home and 10% of the boys have dogs at home. How many students own dogs?
Thoughts? Step-by-step reasoning:
Out of 100 students, half are girls and half are boys so there are 100 / 2 = 50 girls. There are 50 girls out of 100 students means there are 100 - 50 = 50 boys. 20% of the 50 girls have dogs so they have .20 * 50 = 10 dogs. 10% of the 50 boys have dogs so they have .10 * 50 = 5 dogs. The girls have 10 dogs and the boys have 5 dogs so together, they have 10 + 5 = 15 dogs.
Thus, the answer is 15.