Answer:
13 pounds
Explanation:
To find out how many pounds the patient needs to lose in the fourth month, we need to subtract the total weight he has already lost from his goal weight loss.
The patient has already lost 18 1/2 pounds + 11 1/4 pounds + 5 1/4 pounds = 35 pounds.
To reach his goal weight loss, the patient needs to lose 48 pounds - 35 pounds = <<48-35=13>>13 pounds.
Therefore, the patient needs to lose 13 pounds in the fourth month.