Quiz
By HUGH GRAY LIEBER and LILLIAN R. LIEBER
SUPPOSE you have two glasses,
One containing pure water (W),
The other containing
The same amount of pure alcohol (A).
Now suppose you take
One teaspoonful of alcohol
From glass A and
Transfer it to glass W,
Stir it well,
Then take a teaspoonful of
This mixture from W
And put it into the first glass, A.
(Neither glass was originally full,
And hence will not run over
In the process.)
One containing pure water (W),
The other containing
The same amount of pure alcohol (A).
Now suppose you take
One teaspoonful of alcohol
From glass A and
Transfer it to glass W,
Stir it well,
Then take a teaspoonful of
This mixture from W
And put it into the first glass, A.
(Neither glass was originally full,
And hence will not run over
In the process.)
QUESTION : —
Compare the per cent of alcohol
Now present in glass W,
With the per cent of water
Now in glass A: —
(a) Are they the same
(b) Or, if not,
Which is greater?
THE ANSWER is: —
The per cents are the same,
As shown below: —
| A | W | |
|---|---|---|
| 1st step | 4tsp . alcohol (4a) | 4tsp . water (4w) |
| 2 nd step | 3a | 4w + la 1/5 alchol 4w + la 4/5 water |
| 3 rd step | 3 1/5 w + 4/5 a total = 4 tsp | 3 1/5 w + 4/5 a total = 4 tsp |
| 4 th step | 4/5 /4 = 20 per cent alcohol | 4/5 /4 = 20 per cent water |
This will be true no matter what
The specific quantities involved.