Maths Set Theory Puzzle

In a school, there are four subjects. Seventy percent of students study English, seventy five percent of students study Science, eighty five percent of students study Mathematics and eighty percent of students study Spanish.

Can you calculate the percentage of students that study all four subjects?




Similar Riddles

A number with an interesting property:

When I divide it by 2, the remainder is 1.
When I divide it by 3, the remainder is 2.
When I divide it by 4, the remainder is 3.
When I divide it by 5, the remainder is 4.
When I divide it by 6, the remainder is 5.
When I divide it by 7, the remainder is 6.
When I divide it by 8, the remainder is 7.
When I divide it by 9, the remainder is 8.
When I divide it by 10, the remainder is 9.

It's not a small number, but it's not really big, either.
When I looked for a smaller number with this property I couldn't find one.

Can you find it?

Asked by Neha on 21 Nov 2024


Can you name some countries which do not have the alphabet 'A' in them?

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Can you spot the man between the coffee bean in the picture below ?

Spot the Man

Asked by Neha on 31 Aug 2021


In a family supper, a grandfather, a grandmother, two fathers, two mothers, four children, three grandchildren, one brother, two sisters, two sons, two daughters, one daughter-in-law, and one mother-in-law need to sit at a table.

There are only seven chairs available at the place. How many more chairs do they have to borrow so that everyone can sit down together for the suppers if everybody requires a separate chair?

Asked by Neha on 09 Nov 2024

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

Asked by Neha on 18 Jan 2025

If you drop me I’m sure to crack, but give me a smile and I’ll always smile back. What am I?

Asked by Neha on 07 Mar 2025


Using the clues below, what four numbers am I thinking of?

The sum of all the numbers is 31.
One number is odd.
The highest number minus the lowest number is 7.
If you subtract the middle two numbers, it equals two.
There are no duplicate numbers.

Asked by Neha on 06 Jan 2025

Can you write down eight eights so that they add up to one thousand?

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I am the first thing you need while camping.
I am always with the person named Marcos Valencia and Carrick.
But Pogba Zlatan and Rooney think I am wasteful and do not need me.
I am the second to the last thing to add when you are making a patch.

What am I?

Asked by Neha on 16 Dec 2024


John and Jacob are twin brothers. One of them is a liar whereas the other one is a truth-teller.

I called their home number and one of them picked up.
I asked. 'Does John lie?' The person replied with a yes.

Whom did I talk with, John or Jacob?

Asked by Neha on 23 Nov 2024

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Crossword puzzles

In the 1920s, people feared that crossword puzzles would contribute to illiteracy.