Your conclusion would then be that 375 million bottles of shampoo and 190 million bottles of conditioner are required for hotel use every year. To estimate the total market size, you can probably make things easy on yourself by assuming that the number produced for sample purposes is a small percentage of the total, say ten percent. Combining your two markets would give you approximately 400 million bottles of shampoo and 210 million bottles of conditioner. You are in a room with three light switches, each of which controls one of three light bulbs in the next room. Your task is to determine which switch controls which bulb.
All lights are off.
The best way to determine which light bulb is which is to flick one switch on, wait for five minutes and flick it off. Then flick one of the remaining two switches on and leave the other off. Other creative solutions involve pushing the constraints of the game. You might ask if the room you're in has a phone, so you could call somebody to help you. You might ask if the rooms have a connecting window.