Question 36 of 46

That answer is right. There were 72 mg of lidocaine administered to a patient that received 2 cartridges of 2% lidocaine with 1:100,000 epinephrine.

That is because:

there are 1.8 ml of solution in a dental cartridge
a 2% solution contains 20 mg/ml of local anesthetic

Therefore, 1.8 ml multiplied by 2 cartridges times 20 mg/ml equals 72 mg.