Verbal Reasoning - Arithmetic Reasoning - Discussion
Discussion Forum : Arithmetic Reasoning - Section 1 (Q.No. 29)
29.
A farmer built a fence around his square plot. He used 27 fence poles on each side of the square. How many poles did he need altogether ?
Answer: Option
Explanation:
Since each pole at the corner of the plot is common to its two sides, so we have :
Total number of poles needed = 27 x 4 - 4 = 108 - 4 = 104.
Discussion:
12 comments Page 2 of 2.
Shibaemon said:
6 years ago
For those asking why 104, here's a simple visualization. See how they share a common fence.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
2 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 26 **
3 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 25 |
4 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 24 |
5 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 23 |
23 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 5 |
24 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 4 |
25 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 3 |
26 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 2 **
27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
Remember, the fence we are talking about here is NOT the FLAT kind of fence.
Let's take 2 sides, let's say Top and Bottom. Both have 27 fence poles.
Then let's take Left and Right sides. They only have 25 fence poles remaining (still 27 per side but we won't count the other 2 because we already had them accounted in Top and Bottom sides).
That's (27*2)+(25*2) = 104.
or (25*4)+4 common corner = 104.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
2 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 26 **
3 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 25 |
4 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 24 |
5 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 23 |
23 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 5 |
24 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 4 |
25 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 3 |
26 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 2 **
27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
Remember, the fence we are talking about here is NOT the FLAT kind of fence.
Let's take 2 sides, let's say Top and Bottom. Both have 27 fence poles.
Then let's take Left and Right sides. They only have 25 fence poles remaining (still 27 per side but we won't count the other 2 because we already had them accounted in Top and Bottom sides).
That's (27*2)+(25*2) = 104.
or (25*4)+4 common corner = 104.
(1)
Unknown said:
6 years ago
For those who are asking why 4 is subtracted.
Answer:
27 poles on each side.
It means 4 poles were commonly shared by all sides.
By multiplying *4 we are considering those commonly shared poles also. So we are removing 4 poles.
It is like saying a car has 8 wheels instead of 4.
By considering the front and back sides also.
i.e.,
right side = 2 wheels.
Left side = 2 wheels.
Front side =2 wheels.
Backside = 2 wheels.
Answer:
27 poles on each side.
It means 4 poles were commonly shared by all sides.
By multiplying *4 we are considering those commonly shared poles also. So we are removing 4 poles.
It is like saying a car has 8 wheels instead of 4.
By considering the front and back sides also.
i.e.,
right side = 2 wheels.
Left side = 2 wheels.
Front side =2 wheels.
Backside = 2 wheels.
(2)
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