Latest Maths Riddles

In a competitive exam, each correct answer could win you 10 points and each wrong answer could lose you 5 points. You sat in the exam and answered all the 20 questions, which were given in the exam.
When you checked the result, you had scored 125 marks in the test.

Can you calculate how many answers given by you were wrong ?

Two friends hit the accelerator of their respective cars at the same time. Both of them have the same amount of petrol in their respective cars at the time they start. One can drive for 4 hours and the other can drive for 5 hours.
After driving for a while, they analyse that the amount of petrol left in one of their cars is 4 times that of the petrol left in other car.

Can you calculate how long they have been driving their respective cars ?

While trying to pull out a robbery, a criminal came across a password lock. He has the following information with him that can assist him in cracking the password.

Can you help him out?

1. The password is a 5-digit number.
2. The 4th digit is 4 more than the 2nd one.
3. The 3rd digit is 3 less than the 2nd one.
4. The 1st digit is three times the 5th digit.
5. Three pairs of digits sum up to 11.

Two men play a dice game involving roll of two standard dice. Man X says that a 12 will be rolled first. Man Y says that two consecutive 7s will be rolled first. The men keep rolling until one of them wins.

What is the probability that X will win ?

Use the digits from 1 up to 9 and make 100.

Follow the rules.
=> Each digit should be used only once.
=> You can only use addition.
=> For making a number, two single digits can be combined (example, 4 and 2 can be combined to form 42 or 24)
=> A fraction can also be made by combining the two single digits (example, 4 and 2 can be combined to form 4/2 or 2/4)

Question: how can we do this ?

Once upon a time there were three rivals who got together in a dark wood on an open spot for composing a quarrel by using guns. It was a kind of duel but there were three people in it and therefore it is a truel. There were A, B and C. there was some rules to be followed in the game. The rules of the games were:
-They have to draw the lots in order to find who will fire first and who will be second and who will be third.
- The next rule is that, they will start firing on each other unless there is a last person alive.
- Each person will decide on his own about which person he will fire on.
-it is quite clear that A hits and kills in all the shots and it is 100%. Whereas 80% of the shots are hit by B and C hits in 50% of the shots he tries to fire in. the three persons have their own strategy for firing. Nobody is killed by the stray bullet.

Question: who will have the highest chances for surviving in the truel and how much is the chance?

Find out a number which is less than 100 and is more than one fifth of its actual value when the digits are reversed.

James Bond is caught up in a mysterious scenario where the evil villain has him blindfolded. He somehow breaks through the handcuffs but is unable to get the blindfold off. Upon searching, he comes across a bow and 3 arrows. He can hear the villain speak, and thus tries to take a shot at him. He launches the first arrow, it misses the villain. He then launches the second arrow and it misses by a greater margin.

What is the probability that this third shot our james bond takes will be worse than the second shot?

In order to complete the racing competition, the London racetrack has to submit its top and the most famous three horses to win the competition. Due to a electrical storm, all the records are cleared and no one knows which horse holds the record. They all look identical and it becomes even more difficult to differentiate the horses. There are 25 horses in the London racetrack. But there can be only five horses at a time on the track. What will the least number of races that can be conducted to find out the three fastest horses?

There are two variables x and y. Jimmy is required to construct a function f(a,b) which returns the maximum one in {a,b}.
You can only use +,-,·, / & abs() (to take the absolute value). NO if () is allowed in to jimmy.

Solve this one, math freaks.