A hospital dietitian computes the daily calorie intake for a patient as 3000 calories. The calories allowed for lunch are twice the calories allowed for breakfast. The calories allowed for dinner are one and one-half the calories allowed for lunch. The allowance for an evening snack is 180 calories. How many calories are allowed for lunch?
Let:
x = calories allowed for breakfast
2x = calories allowed for lunch
(2x) * (3/2) = 3x = calories allowed for dinner
The total calorie intake for the day is given as 3000 calories. Thus:
x + 2x + 3x + 180 = 3000
6x + 180 = 3000
6x = 2820
x = 470
Therefore, the calories allowed for lunch is 2*470 = <<2*470=940>>940 calories. Answer: \boxed{940}.