How can you help to pour out the juice so that each will get their 400ml of juice?

Question

there are 2 bottles of juice each of capacity 800ml.. these are be shared among 4 friends so that each will get 400ml.. there is no measuring instruments to measure out the exact volume but there are 2 glasses that can measure out exactly 300ml each.. you can't make your own markings and there is no markings on the glasses

Answer 1

here is how you start this then repeat

pour 300 ml from each 800 into the 300 ml glasses

leave 500 ml in the 800 ml bottles

pour from one of the 800 ml bottles and fill the other 800 ml bottle

this leave 200 ml in this bottle, give this to one of the 1 to

drink

you now have three glasses with 800, 300 and 300 ,0 mls

pour the 1, 300 mls into the 800 ml glass (300 ml)

not pour refill that bottle from the 800, this leave 500 ml

then pour from the b with 500 into the 300 ml, and give the rmaining 200 ml to the friend who just drank the other 200ml

you now have left 1200 ml of drink

fill one of the 800 ml bottles, from the other three glasses

now one has 800 ml and the others have 400 miles, give that to one of the friends,

so now you have 1 800 ml bottle

again, fill the one glass with 300, then pour that into the empty 800 bottle, then from the bottle with 500 ml, fill the 300 ml glass, there is 200 ml left, empty one of the 300 ml into the other 800 ml bottle, then fill that glas with 200 ml from the 500 ml bottle, now fill that glass up, you have one glass with

I almost had it but can seem to finish

I need another glass to play with. 2 300 ml is not enough

Answer 2

fill both glasses from one bottle, leaves 200 in bottle

person1 and person2 each drink their 300 from the glasses

repeat with second bottle, person3 and person4 each getting a 300ml glass

this leaves 2 bottles each with 200 in.

pour one bottle into two glasses until the levels are equal, this is 100 in each glass for 2 people

repeat with other bottle for the last 2 persons' 100ml topup

Answer 3

The key here is that it's not possible to give everyone a container with their entire 400ml serving, since the glasses can only hold 300ml and there's no spares.  So you're going to have some drinking happening during the process.  And it won't necessarily be sanitary.