How Much Time is Left in the Exam?

During a math exam, Willy asks Ms. Matilda, the teacher, how much time is left. Ms. Matilda is known for being obtuse and answers that the amount of time left is 1/5 of the time already completed and that is also how much time is left, in a manner of speaking.

How much time is left?

15 minutes. The total exam time is 90 minutes. If 15 minutes are left, 75 minutes have already passed, and one fifth of 75 is 15. However, if you follow Ms. Matilda’s hint and pay attention to only the numbers in 1/5, you get the answer of 15 minutes as well.

Posted in Brain Teasers


9 Comments on "How Much Time is Left in the Exam?"

William says
April 30, 2015 @ 02:30

1X minute(s) left, 6X minute(s) total and 1X minute(s) has passed.

Note: minute(s) could also be replaced with hour(s), second(s) or any other measurement of time.

Dan says
April 30, 2015 @ 09:49

That’s a good point. It doesn’t have to be minutes.

Miranda says
April 12, 2016 @ 09:57

1/5 is meant by 15 minute

Neo says
September 10, 2016 @ 21:22

It may be,
remaining =5 minutes
already completed time = 25 minutes
total time for examination = 30 minutes
remaining = 20 minutes
already completed time= 100 minutes
total time for examination = 120 minutes

I got some other answers too, but i don’t know which one is right…
somebody please explain. because , it gives more than one possible answers..

Catalin says
January 26, 2017 @ 12:28

You dont mean this exercise do you?

You start to explain the answer with the 15 minutes? why not 10 or 5.. dude .. wtf!

Idvvkwvowj says
April 20, 2017 @ 17:37

15 ovbs

Idvvkwvowj says
April 20, 2017 @ 17:38

Look at the time I submitted this comment

Merlin says
May 26, 2018 @ 07:56

A fifth of Bourbon for the fifteen minutes it took for us to figure it out…

Stavros says
July 22, 2018 @ 02:10

Since the riddle doesn’t State how long the exam is. Only miss Matilda and Willie actually know what one fifth of the remaining time should be. Anything else would just be pure speculation, there is no set time on the exam for us to draw a conclusion from and poor Willie might not even know how long the exam is that’s why he’s asking how much time is left in the first place.

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