Q) Suppose you have a 3 liter jug and a 5 liter jug. The jugs have no
measurement lines on them either. How could you measure exactly 4 liter using
only those jugs and as much extra water as you need?
ANS :
Step 1 :
First, fill the 5 liter jug and then pour it into the 3 liter jug. The 5 liter
jug now has only 2 liters left.
Step 2 : Next, empty out the 3 liter jug. Then, pour the 2 liters from the 5 liter jug to the 3 liter jug. So, now the 3 liter jug has 2 liters.
Step 3 : Fill the 5 liter jug again, and pour 1 liter into the 3 liter jug. Now, what’s left in the 5 liter jug? Well, exactly 4 liters! There’s your answer.
Q) There are 3 baskets labeled
‘Apples’, ‘Oranges’ & ‘Mixture’. One of them contains only Apples, one only
Oranges and one has mix of apples and oranges both.
These baskets are not labeled correctly. In fact, the labels on
these baskets always lie. (i.e. if the label says Oranges, Then you are sure
the basket either has only Apples or Mixture).
You are allowed to pick one fruit from one basket (Not allowed to
see other fruits), and you have to put all the labels correctly on the basis of
that information (by seeing only one fruit from any one basket).
How will you do that ?
ANS:
Pick a fruit from the basket labeled
‘Mixture’. We know from the question that this basket does not contain
‘Mixture’ for sure.
- If this fruit is an apple, then label this Basket as ‘Apple’ (Because this basket does not contain Mixture, so if one is apple, all are apples only). Now we’ve determined that the basket labeled as ‘Mixture’ only contains Apples.
- If we look at the basket labeled as ‘Oranges’, we know that since the label is incorrect, this basket either has only apples in it or has Mixture. Since we already know which basket contains only apples, we know that the basket labeled as ‘Oranges’ contains ‘Mixture’. So label it as ‘Mixture’. The 3rd basket will be labeled as ‘Oranges’.
You can apply the same logic if you
assume you initially picked an orange from the basket labeled as ‘Mixture’
Q) You have two
sticks and matchbox. Each stick takes exactly an hour to burn from one end to
the other. The sticks are not identical and do not burn at a constant rate. As
a result, two equal lengths of the stick would not necessarily burn in the same
amount of time. How would you measure exactly 45 minutes by burning these
sticks?
ANS: This
puzzle used to be asked in Wall Street interviews long time ago. It is
very rare for this question to be asked now but it is a very good question to
help you think a little outside the normal thought process.
The answer is really simple. Since
the sticks do not burn at a constant rate, we can not use the length of the
stick as any sort of measurement of time. If we light a stick, it takes 60
minutes to burn completely. What if we light the stick from both sides? It will
take exactly half the original time, i.e. 30 minutes to burn completely.
0 minutes – Light stick 1 on both sides
and stick 2 on one side.
30 minutes – Stick 1 will be burnt out. Light the other end of stick 2.
45 minutes – Stick 2 will be burnt out.
30 minutes – Stick 1 will be burnt out. Light the other end of stick 2.
45 minutes – Stick 2 will be burnt out.
For more Questions below are the
references
