100+ Detective Riddles Inspired by Sherlock Holmes and Detective Mehul

Who Is The Girlfriend

1.Detective Riddles

Dhamaka Singh  escapes from prison with the help of his girlfriend.

Detective Mehul suspect four girls of being the Dhamaka Singh's  girlfriend.

Out of those four girls, one is his girlfriend who is lying. Two of the girls are completely innocent and are speaking the truth. One of the girls is the man`s sister who is helping the girlfriend lie.

Following are the statements from all four of them:

Adriana: "Mary is his girlfriend."

Jenny: "Angel is lying."

Angel: "Adriana is lying."

Mary: "Jenny is not his sister."

Can you find out the Dhamaka Singh`s girlfriend and sister among these 4 girls ?

Adriana
Mary
Angel
Jenny

Explanation :  Suppose if Adriana is his sister and we know that his statement is false.

This will mean that Mary is not his girlfriend.

If Angel is telling the truth, then Adriana must be lying that we have already assumed.

If Jenny is his girlfriend, then she must have spoken a lie as well.

This will mean Angel is speaking the truth which is true in what we have assumed.

At last, Mary said that Jenny is not his sister which is also true as we have made the assumption already that Jenny is his girlfriend.

In what we have assumed, all the statements fit perfectly and the given conditions are satisfied. If you make any other assumption, you will find that one or more conditions are not fulfilled.

Adriana is the sister and Jenny is the girlfriend.

An Aeroplane Hijack

2.Detective Riddles

Dhamaka Singh hijacks an aeroplane transporting both passengers(8 of them) and valuable cargo. After taking the cargo, Dhamaka Singh demands nine parachutes, puts one of them on, and jumps, leaving the other eight behind. Why did he want eight parachutes?

If the officials thought he was jumping with a hostage, they would never risk giving him a faulty parachute.

Who Broke The Window Mystery

3.Detective Riddles

One snowy night Detective Mehul was in his house sitting by a fire. All of a sudden, a snowball came crashing through his window, breaking it. Mehul got up and looked out the window just in time to see three neighbourhood kids who were brothers run around a corner. Their names were John Crimson, Mark Crimson and Paul Crimson.

The next day Detective Mehul got a note on his door that read "? Crimson broke your window."

Which of the three crimson brothers should Detective Mehul question about the incident?

Mark Crimson "?" = question MARK, so the note on the door reads "Question Mark Crimson broke your window."

Friday Be An Unlucky Day

4.Detective Riddles

One day a kid challenges Riddle master Gogo to solve a riddle. The child claimed that he was smarter than Gogo.

As soon as Gogo accepted the challenge, the child asked him, "Many people would think Friday the 13th will be an unlucky day. Is it possible that there is no Friday on 13th through the whole year? How many Fridays at 13th can we have in a year at most? Can you calculate it out?" Gogo solved the riddle and proved himself smarter. How did he do it, can you calculate ?

Gogo thought to himself," I can calculate out how many days there will be for the 13th on each month if i count from the beginning of the year (January 1). Then i can divide total days by 7 to get the remainders. I will also need to consider the leap year. Through the whole year i  had all kinds of remainders, from 0 to 6. The minimum of occurrence for all the unique remainders was 1. It means that there is at least one Friday on 13th. In a regular year, the best chance you  can get 3 Fridays on 13th, which are in February, March and December because the remainders of these 3 months are 2. In a leap year, the best chance you also can get 3 Fridays on 13th, which are in January, April and July because the remainders of these 3 months are 6.

Kushal The Killer

5.Detective Riddles

Kushal is  living at  alone place. He own a shed which has been locked. The lock that has been placed on the door can be closed without a key but need the key to be opened.

He collected some old stuff and decided to keep it in the shed. After keeping the things, he locked it back. The next day, the police found a dead body inside the shed. As Kushal is the only one living in house, the police has nothing else to believe than Kushal is the murderer.

But Kushal have not committed any crime. There is a way the murder would have happened. Can Kushal find that way and tell the police so he is not sentenced for the crime he did not commit?

(Hint :The main hint here is that the lock can be closed without a key, so think about it and Kushal will get the answer.)

The lock can be closed without a key.

When Kushal were keeping the things inside the shed, the murderer took the lock hanging on the door and replaced it with an identical one.

Kushal closed it as it did not require a key. When  Kushal were gone, the murderer opened the new lock with his key, planted the body inside, replaced the lock with the original one again and locked it.

The Famous Elevator Puzzle

6.Detective Riddles

Gogo the riddle Master  lives on the tenth floor takes the elevator down to the first floor every morning and goes to work. In the evening, when Gogo comes back; on a rainy day, or if there are other people in the elevator, he goes to his floor directly. Otherwise, he goes to the seventh floor and walks up three flights of stairs to his apartment.
Can you explain why?

Gogo is a of short stature. He can't reach the upper elevator buttons, but can push is with his umbrella.

Aalia's Eggs and 100 Floors Puzzle

7.Detective Riddles

Aalia participates in a show where she is given a task which she has to complete in order to win the cash prize. She is given 2 eggs. She has access to a 100-storey building. Eggs can be very hard or very fragile means it may break if dropped from the first floor or may not even break if dropped from 100 the floor.Both eggs are identical. She needs to figure out the highest floor of a 100-storey building an egg can be dropped without breaking. How many drops she needs to make when she is allowed to break 2 eggs in the process.

Let x be the answer Aalia wants, the number of drops required.

So if the first egg breaks maximum she can have x-1 drops and so she must always put the first egg from height x. So she has determined that for a given x she must drop the first ball from x height. And now if the first drop of the first egg doesn't breaks she can have x-2 drops for the second egg if the first egg breaks in the second drop.

Taking an example, if 16 is her answer. She needs 16 drops to find out the answer First She drops from height 16,and if it breaks she tries all floors from 1 to 15. If the egg doesn't break then she has left 15 drops, so she will drop it from 16+15+1 =32nd floor. The reason being if it breaks at 32nd floor she can try all the floors from 17 to 31 in 14 drops (total of 16 drops). Now if it did not break then she is left with 13 drops. and she can figure out whether she can find out whether she can figure out the floor in 16 drops.

Lets take the case with 16 as the answer

1 + 15 16 if breaks at 16 checks from 1 to 15 in 15 drops
1 + 14 31 if breaks at 31 checks from 17 to 30 in 14 drops
1 + 13 45 .....
1 + 12 58
1 + 11 70
1 + 10 81
1 + 9 91
1 + 8 100 We can easily do in the end as we have enough drops to accomplish the task

Now finding out the optimal one she can see that she could have done it in either 15 or 14 drops only but how can she find the optimal one. The optimal one will be needing 0 linear trials in the last step.

So she could write it as

(1+p) + (1+(p-1))+ (1+(p-2)) + .........+ (1+0) >= 100.

Let 1+p=q which is the answer she is looking for

q (q+1)/2 >=100

Solving for 100 she gets q=14.
So the answer is: 14
Drop first orb from floors 14, 27, 39, 50, 60, 69, 77, 84, 90, 95, 99, 100... (i.e. move up 14 then 13, then 12 floors, etc) until it breaks (or doesn't at 100)

The Statuette Robbery

8.Detective Riddles

Kushal was alone at home and heard that something had fallen in his wife`s room. He entered and saw that her favourite statuette was broken. At that moment someone ran out of the room.

Kushal tried to catch up with the stranger. But in the street the lenses on his eyeglasses fogged up because of cold weather. He could see nothing, giving the stranger the opportunity to disappear.

Kushal told this story to Detective Mehul, but he refused to investigate the case. Mehul asked him to stop lying and admit that it was he who had broken the statuette.Was Kushal`s story fake?

Yes, it was. Kushal ran out into the street while chasing a stranger. But eyeglass lenses don`t fog up when a person comes out of a warm room and into the cold. He was just afraid to confess to his wife that he had broken her favourite statuette.

Old Man Murder Mystery

9.Detective Riddles

A wealthy man lives alone in a small cottage. Being partially handicapped, he had everything delivered to his cottage. The mailman was delivering a letter one Thursday when he noticed that the front door was ajar. Through the opening he could see the man's body lying in a pool of dried blood. When Detective Mehul arrived he surveyed the scene. On the porch were two bottles of warm milk, Monday's newspaper, a catalog, flyers, and unopened mail. The police officer suspects it was foul play. Who does he suspect and why?

Detective Mehul suspects the newspaper delivery person. The absence of Tuesday's and Wednesday's newspapers indicates that the delivery person knew there was no one there to read them.

Who Stole Animals

10.Detective Riddles

A hen, a dog and a cat are stolen. Three suspects are arrested named Jagga, Dhamaka Singh and Gogo. The police are sure that each of them has stolen one of the animals but they don?t know who stole which animal.

Detective Mehul  is appointed to identify and is provided with the following statements from the investigation.

Mehul is somehow able to deduce that the man who stole the cat is telling a lie and the man who stole the hen is telling truth. Can you help him find out who stole which animal?

Glance at the first and second statement again; they are contradictory. Both can be true together though. Also both of them cannot be false which means that Gogo stole cat and his statement will be true. But it has been already deduced that the one who stole cat was telling a lie thus it can?t be possible.

Let us consider the situation again. It may be that Gogo stole a hen or a dog. Assume that he stole hen. In such a case the statement of Gogo will be false. But we know that the person who stole hen told the truth, thus it is contradicting our assumption and so cannot be correct.
Considering everything, now we can say with confidence that Gogo stole the dog.

Now it means that the statement by Jagga is completely false and the statement by Dhamaka Singh is true which depicts that the cat and hen are stolen by these two. Also we know that the one who stole hen is true and the one stealing cat is a liar. Thus we now know that Jagga stole cat and Dhamaka Singh stole hen.

Hence we can deduct the following as our answer;

Jagga Stole Cat

Dhamaka Singh stole Hen

Gogo Stole Dog