Question

18 to 29=10%

30 to 49=30%


Suppose Max knows that 45 people with ages of 18 to 29 voted. Without using a calculator he then says 135 people with ages of 30 to 49. Is he correct? How might Max have come up with his answer so quickly?

Answer 1

45 people is 10% of 450.
So how many people is 30% of 450.

1. Multiply (45)(3) = 135. Because 30% is 3 times 10%.
2. Multiply (450)(.3) = 135. Because .3 = 30% in decimal form.