Answer
a) Two tablets contain 67 mg of aspirin.
b) The dosage rate is 0.94 mg of aspirin per kg body mass.
c) It takes $1.5 * 10^{4}$ days to consume 1 kg of aspirin.
Work Step by Step
a) 2 aspirin tablets contain 2 * 5.0 = 10.0 gr of aspirin.
15 gr = 1.0 g
1 gr = 1.0 / 15 g = 0.06666666667 g
10.0 gr = 0.6666666667 g
0.6666666667 g = 66.66666667 mg
Rounding to 2 significant figures gives 67 mg.
So two tablets contain 67 mg of aspirin.
b) Body mass = 155 lb
2.205 lb = 1 kg
1 lb = 1/2.205 kg = 0.4535147392 kg
155 lb = 155 * 0.4535147392 kg = 70.29478458 kg.
Dosage rate = 66.66666667 mg of aspirin per 70.29478458 kg body mass.
This is 66.66666667 / 70.29478458 mg of aspirin per kg body mass.
This is 0.943870968 mg of aspirin per kg body mass.
Rounding to 2 significant figures gives 0.94 mg of aspirin per kg body mass.
c) Rate of consumption = 2 tablets per day.
2 tablets contain 66.66666667 mg of aspirin (see a).
1 kg = $10^{6}$ mg
$10^{6}$ / 66.66666667 = 15000 days.
So at the given rate of consumption it takes 15000 days to consume 1 kg of aspirin.
Rounding to 2 significant figures gives 1.5 * $10^{4}$ days.
