To find the range of the function \( c = 30.75u + 5.75 \) given that \( u \) (the number of uniforms) is at least 8 but not more than 12, we will evaluate the function at the endpoints of this interval.
-
Calculate the cost when \( u = 8 \): \[ c(8) = 30.75(8) + 5.75 \] \[ c(8) = 246 + 5.75 = 251.75 \]
-
Calculate the cost when \( u = 12 \): \[ c(12) = 30.75(12) + 5.75 \] \[ c(12) = 369 + 5.75 = 374.75 \]
Now, we have calculated the cost for both cases:
- When \( u = 8 \), \( c = 251.75 \)
- When \( u = 12 \), \( c = 374.75 \)
Since \( c \) is a linear function that increases as \( u \) increases, the range of the function for \( u \) in the interval \([8, 12]\) is: \[ [251.75, 374.75] \]
Therefore, the range of the function for the given situation is: \[ \boxed{[251.75, 374.75]} \]