Where Should You Place 8 Marks on a Blank 36 cm Ruler?

  • Thread starter Greg Bernhardt
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In summary, with a blank ruler (without marks) of exactly 36 cm, you can only measure 36 cm. To be able to read off all full centimeter values from 1 to 36 cm directly from the ruler, you must set 8 marks at 1 cm intervals, starting at 1 cm and ending at 35 cm. This can be achieved by placing the first mark at 1 cm, and then placing the remaining marks at 3 cm, 6 cm, 13 cm, 20 cm, 27 cm, 31 cm, and 35 cm. This allows for accurate measurement of all full centimeter values from 1 to 36 cm without any copying or using the ruler twice.
  • #1
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With a blank ruler (without marks) of exactly 36 cm you can only measure 36 cm. Now you are allowed to set 8 marks so that you can read off all full centimeter values from 1 to 36 cm directly from the ruler.

Where must these 8 marks be?
 
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  • #2
At the beginning, and a centimeter apart each, is my guess.
 
  • #3
Originally posted by Mentat
At the beginning, and a centimeter apart each, is my guess.

You can only have eight marks
 
  • #4
You place the firts mark at 4 cm and then following 4 cm after. Therefore, you have a mark at 4, 8, 12, 16, 20, 24, 28, 32.
 
  • #5
0,5 cm
1,0 cm
3,0 cm
6,0 cm
10,0 cm
15,0 cm
21,0 cm
28,0 cm

just guessing [?]
 
  • #6
No idea. Every 4.5 centimeters?


Also to point out about the last brain teaser, I would have said compressed gasses (as it seems recent planetary science has led to the idea that outter planets would not have enough rocky material that far out to form large rocky cores. Mainly from evidence from exosolar systems, but ultimately I suppose it is the accepted answer).
 
  • #7
Originally posted by iansmith
You place the firts mark at 4 cm and then following 4 cm after. Therefore, you have a mark at 4, 8, 12, 16, 20, 24, 28, 32.

How do you measure 3cm or 5cm then?
 
  • #8
maybe it's time for another wild guess, how about:

1,0 cm
2,0 cm
3,0 cm
4,0 cm
5,0 cm
6,0 cm
7,0 cm
8,0 cm

together they add up to 36 cm
 
  • #9
First at 18 in the middle
Then at 9
At 4.5
Divide that space in 3 so you have 1.5 and 3.0
And divide the 3.0 marking into 3 as well.
 
  • #10
*after you have the first centimetre then you can copy the 1 cm length over the ruler to measure everything
 
  • #11
Originally posted by cytokinesis
First at 18 in the middle
Then at 9
At 4.5
Divide that space in 3 so you have 1.5 and 3.0
And divide the 3.0 marking into 3 as well.

all full centimeter values from 1 to 36 cm directly from the ruler. how do you find 5cm?
after you have the first centimetre then you can copy the 1 cm length over the ruler to measure everything
Nah, that's cheating, you must be able to read all full centimeter values from 1 to 36 cm directly from the ruler. no copying or using the ruler twice.
 
  • #12
I will mark
1, 3, 6, 13, 20, 27, 31, and 35 centimeters on my ruler.
 
  • #13
Originally posted by Hurkyl
I will mark
1, 3, 6, 13, 20, 27, 31, and 35 centimeters on my ruler.

Hurkyl wins the point! btw Hurkyl check your pm
 

1. What is the blank ruler riddle?

The blank ruler riddle is a popular mathematical puzzle that involves finding the length of an object using only a blank ruler and a set of measurements.

2. How does the blank ruler riddle work?

The riddle presents a scenario where a person needs to find the length of a table or other object using only a blank ruler, which has no markings. The person is given a set of measurements, such as the width of the object, the distance between two points on the object, and the length of the ruler. The challenge is to use these measurements to determine the length of the object.

3. What is the solution to the blank ruler riddle?

The solution to the blank ruler riddle involves using basic algebraic equations to find the missing measurements. By setting up equations with the given measurements and unknown lengths, the length of the object can be determined.

4. What skills are required to solve the blank ruler riddle?

To solve the blank ruler riddle, one must have a basic understanding of algebra and geometry. Additionally, critical thinking and problem-solving skills are necessary to approach the riddle in a logical and systematic manner.

5. Why is the blank ruler riddle important?

The blank ruler riddle is a fun and challenging way to exercise mathematical and problem-solving skills. It also encourages creative thinking and helps develop logical reasoning abilities. These skills are essential in many fields, including science, engineering, and technology.

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