Texas Class A Barber Written ExamSanitation, Disinfection, and SafetyHard
A barber is using a new disinfectant concentrate that requires a 1:128 dilution ratio. If the barber needs to make 1 gallon of ready-to-use solution, how much disinfectant concentrate should be added to the water?
- A4 fluid ounces
- B0.5 fluid ounces
- C2 fluid ounces
- D1 fluid ounce
Show answer & explanationAnswer & explanation
Correct answer: D. 1 fluid ounce
A 1:128 dilution means 1 part concentrate to 128 parts total solution. To make 1 gallon (128 fluid ounces) of solution, you need 1 fluid ounce of concentrate. (1 gallon = 128 fluid ounces. 128 fluid ounces / 128 parts = 1 fluid ounce per part).
Why the other options are wrong
- A. 4 fl oz would result in a 1:32 dilution, which is significantly too strong.
- B. 0.5 fl oz would result in a 1:256 dilution, which is too weak.
- C. 2 fl oz would result in a 1:64 dilution, which is too strong.
Dilution Ratio Calculation (1:128)
To achieve a 1:128 dilution for 1 gallon of solution, 1 fluid ounce of concentrate is needed, as 1 gallon equals 128 fluid ounces.
- 1 gallon = 128 fluid ounces.
- Ratio X:Y means X parts concentrate to Y total parts solution.
- Calculation: (Total volume / Y) * X = amount of concentrate.
Memory trick: Gallons are 128, so 1:128 means one ounce to save your labor!