Some more puzzles which are asked in interviews

Puzzles are asked in interviews to check how you approach something unknown. Puzzles are usually asked in product-based companies and roles requiring logical thinking.

Here are some more puzzles to practice for interviews.

1. Beetles and spiders

Naval collected 8 spiders and beetles into a little box. When he counted the legs he found that there were altogether 54.

How many beetles and how many spiders did he collect? Spider has 8 legs and beetles 6.

Answer: 3 spiders and beetles

Suppose there are only 8 beetles, then there should be 48 legs.

Now suppose 7 beetles and 1 spider, then total legs increase by 2 hence, 50.

Similarly for 6 beetles and 2 spiders, 52.

And for 5 beetles and 3 spiders, 54 legs

2. Weight of a brick

We have a brick of regular size. It weighs 4 kg. How much do you think a similar brick, 4 times smaller, but made of the same material weigh?

Answer: 62.5 g

The smaller brick would not only be 4 times shorter, but also 4 times narrower and 4 times lower.

Hence its volume would decrease by 64 times.

So weight = 4000/64 =62.5 g

3. A problem of ping-pong

There are 150 members in my club. We decided to have a ping-pong tournament. All the members came forward to play in the game. Every time a member loses a game, he is out of the tournament.

There are no ties.

Can you tell how many games must be played in order to determine the champion?

Answer: 149

Since all but one lose one game, 150-1 = 149 games should be played.

Interview Tips

4. A problem of weight

In my neighborhood lives a man who weighs 200 pounds. He has 2 sons. They both weigh 100 pounds each.

On a festival day, they decide to go across the river on a boat to visit some relatives. But the boat could carry a maximum load of only 200 pounds.

How did they across the river by boat?


First the 2 sons rowed across the river. One stayed behind while other came back.

Then the father crossed the river and other son took the boat to this side.

At last both the sons crossed the river.

Success Secrets

5. Average speed

It was a long drive. I drove 60 Km at 30 km per hour and then an additional 60 km at 50 km per hour.

Compute my average speed over the 120 km journey.

Answer: 37.5 kmph

Time for first 60 km: 120 minutes

Time for second 60 km: 72 minutes

Average speed: total distance/total time = (120*60)/192 = 37.5 km per hour

Here is how to approach puzzles.

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