The half-life of aspirin is about 3 hours. If someone takes 700mg, how long will it take until less than 50mg is left in that person's body?

In 3 hours half of 700 would be 700/2=350

in 3 more hours, so 6 total, the half life would be 350/2 = 175

in 3 more hours, 9 total, the half life would be 175/2 = 87.5

in 3 more hours, 12 total, the live life would be 87.5 / 2 = 43.75

so it would be 12 hours to have less than 50 mg