A certain antihistamine is often prescribed for allergies. A typical dose for a 100-pound person is 19 mg every six hours. Complete parts (a) and (b) below. a. Following this dosage, how many 13.6 mg chewable tablets would be taken in a week? b. This antihistamine also comes in a liquid form with a concentration of 13.6 mg/9 mL. Following the prescribed dosage, how much liquid antihistamine should a 100-pound person take in a week?

Step 1 ：First, we need to determine how many doses a person takes in a week. There are 24 hours in a day, so a person takes \( \frac{24}{6} = 4 \) doses per day. Over a week (7 days), this amounts to \( 4*7 = 28 \) doses.

Step 2 ：Each dose is 19 mg, so over a week, a person takes \( 28*19 = 532 \) mg of the antihistamine.

Step 3 ：Each chewable tablet contains 13.6 mg of the antihistamine. Therefore, the number of tablets taken in a week is \( \frac{532}{13.6} = \) approximately 39.12 tablets.

Step 4 ：Since we can't take a fraction of a tablet, we round up to the nearest whole number. Therefore, a person would take \(\boxed{40}\) tablets in a week.

Step 5 ：The liquid form of the antihistamine has a concentration of 13.6 mg/9 mL. Therefore, the volume of liquid antihistamine taken per dose is \( \frac{19}{13.6}*9 = \) approximately 12.57 mL.

Step 6 ：Over a week, a person would take \( 12.57*28 = \) approximately 352 mL of the liquid antihistamine.

Step 7 ：Therefore, a 100-pound person should take approximately \(\boxed{352}\) mL of the liquid antihistamine in a week.