A student wants to purchase a wallpaper border for a bedroom......

Perimeter = 2(12+13) = 50 ft

Roll = 8 yds/roll = 24 ft/roll

# of rolls needed = 50/24 = 2 + 1/12 rolls ~ 3 rolls

So the student made two mistakes - Incorrect conversion + incorrect rounding

This choice is not included in the list - this is why I do not like multiple choice questions.

By the way, I kept misreading the data of the problem. I kept thinking the wall paper was 8 ft/roll instead of 8 yds/roll.

See @Jomo, I am not always right. Sometimes I do support Lenin - and then I have to slap my head.
 
P=2
Subhotosh Khan said:
Perimeter = 2(12+13) = 50 ft

Roll = 8 yds/roll = 24 ft/roll

# of rolls needed = 50/24 = 2 + 1/12 rolls ~ 3 rolls

So the student made two mistakes - Incorrect conversion + incorrect rounding

This choice is not included in the list - this is why I do not like multiple choice questions.

By the way, I kept misreading the data of the problem. I kept thinking the wall paper was 8 ft/roll instead of 8 yds/roll.

See @Jomo, I am not always right. Sometimes I do support Lenin - and then I have to slap my head.
Click to expand...
Great!. Lol. Well, according to Jomo, you're always right!. Just joking ?
 
Nowadays, tests are multiple choice. I don't like it either. Unfortunately, I have to prep for that style of testing too. Don't forget I'll be taking a test next year and it's multiple choice.
 
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Subhotosh Khan said:
Perimeter = 2(12+13) = 50 ft

Roll = 8 yds/roll = 24 ft/roll

# of rolls needed = 50/24 = 2 + 1/12 rolls ~ 3 rolls

So the student made two mistakes - Incorrect conversion + incorrect rounding

This choice is not included in the list - this is why I do not like multiple choice questions.

By the way, I kept misreading the data of the problem. I kept thinking the wall paper was 8 ft/roll instead of 8 yds/roll.

See @Jomo, I am not always right. Sometimes I do support Lenin - and then I have to slap my head.
Click to expand...
Doc, I m in doubt here.
1y=3ft
8 yards* 3 = 24

you wrote; # of rolls needed = 50/24 = 2 + 1/12 rolls ~ 3 rolls
where do you get the 2 + 1/2
as far as I see, the problem says 8 yards and 10 inches wide
Did not get that.
 
It clearly says where the 2 + 1/12 came from! It came from 50/24.

This is why you need to use valid equal signs! Otherwise equals signs mean nothing to you.

What do you get when you divide 50 by 24? You need to review arithmetic!
 
Jomo said:
It clearly says where the 2 + 1/12 came from! It came from 50/24.

This is why you need to use valid equal signs! Otherwise equals signs mean nothing to you.

What do you get when you divide 50 by 24? You need to review arithmetic!
Click to expand...
ohh,
50ft /24ft = 2.08333333333
Got it, got lost for a minute there, thanks,
I understand now why Dr Khan says rounding is also a choice. Yes, it is.
 
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Sorry. Not at home now. Away from my desktop. That is where I focus the most. But I need to keep working on the cellphone. I went back to work. Not home until 6 o'clock now so most of the time I would be on my cell posting and answering.
 
Hello,
Here is my approach to finding the answer. I will find the area and then we can see how it goes.

A student wants to purchase a wallpaper border for a bedroom. The border is sold in rolls 8 yards long and 10 inches wide. The room measures 12 feet by 13 feet. By performing the following operations, the student determines that 6 rolls of the border are needed.

Which statement best explains the student's mathematical error?

Choose an answer
  1. The student rounded incorrectly and thought only 6 rolls were needed.
  2. The student found the perimeter instead of the area of the room.
  3. The student did not change all of the dimensions to the same units.
  4. The student used an incorrect formula for the perimeter.

For my convenience, I converted all the units to a centi meter.
We have the following information
1 paper roll = 8 Yards length and 10 inches width
The area of the wall = 12 feet by 13 feet

8 yards = 731.52 cm
10 inches = 25.4 cm
12 feet = 365.76 cm
13 feet = 396.24 cm

Area of one paper roll = length * width
= 731.52 * 25.4
= 18580.608 cm ^ 2
Area of the wall = length * width
= 365.76 * 396.24
= 144928.7 cm ^ 2

Number of rolls required for the wall = (Area of the wall / Area of one paper roll)
= (144928.24 / 18580.608)
= 7.8 cm ^ 2

The perimeter of the paper roll assuming it is a rectangle: 2 (length + breadth)
2 (731.52 + 25.4) = 1513.84 cm
The perimeter of the wall assuming it is a rectangle = 2 (length + breadth)
= 2 (365.76 + 396.24)
= 1524

Perimeter = 1524 / 1513.82
= 1
 
JasonTurner said:
Hello,
Here is my approach to finding the answer. I will find the area and then we can see how it goes.

A student wants to purchase a wallpaper border for a bedroom. The border is sold in rolls 8 yards long and 10 inches wide. The room measures 12 feet by 13 feet. By performing the following operations, the student determines that 6 rolls of the border are needed.

Which statement best explains the student's mathematical error?

Choose an answer
  1. The student rounded incorrectly and thought only 6 rolls were needed.
  2. The student found the perimeter instead of the area of the room.
  3. The student did not change all of the dimensions to the same units.
  4. The student used an incorrect formula for the perimeter.

For my convenience, I converted all the units to a centi meter.
We have the following information
1 paper roll = 8 Yards length and 10 inches width
The area of the wall = 12 feet by 13 feet

8 yards = 731.52 cm
10 inches = 25.4 cm
12 feet = 365.76 cm
13 feet = 396.24 cm

Area of one paper roll = length * width
= 731.52 * 25.4
= 18580.608 cm ^ 2
Area of the wall = length * width
= 365.76 * 396.24
= 144928.7 cm ^ 2

Number of rolls required for the wall = (Area of the wall / Area of one paper roll)
= (144928.24 / 18580.608)
= 7.8 cm ^ 2

The perimeter of the paper roll assuming it is a rectangle: 2 (length + breadth)
2 (731.52 + 25.4) = 1513.84 cm
The perimeter of the wall assuming it is a rectangle = 2 (length + breadth)
= 2 (365.76 + 396.24)
= 1524

Perimeter = 1524 / 1513.82
= 1
Click to expand...
Sorry, I forgot to thank you for your input. Never saw the last post till a few days ago.
I wonder why nobody said anything. I would have liked the tutors who contributed to refute this because this is different form the answer th answer that was agreed upon by all tutors who contributed. I am sure they must not seen it otherwise they would have commented. Let's see, thanks anyways!!!!.
 
eddy2017 said:
Sorry, I forgot to thank you for your input. Never saw the last post till a few days ago.
I wonder why nobody said anything. I would have liked the tutors who contributed to refute this because this is different form the answer th answer that was agreed upon by all tutors who contributed. I am sure they must not seen it otherwise they would have commented. Let's see, thanks anyways!!!!.
Click to expand...
That answer really doesn't need refutation. But you can refute it yourself.

JasonTurner calculated area rather than perimeter (as if the paper were to be used to cover the floor!); used centimeters, which wastes effort and invites error; and, at the end, found the perimeter of the paper which is utterly silly. Moreover, he didn't answer the question. This is not someone you need to pay attention to.

You were right that the student made the mistake of not converting to the same unit. There are other issues that have been rightly (and wrongly, at times) discussed. To me, the main point of the problem is to interpret how a border is used and how the dimensions of a room are stated, which is not really a math problem, but a test of background knowledge.

I dislike the problem particularly in that it forces you to think through wrong approaches to the problem, rather than helping you keep your attention on correct thinking. It may be a good exercise for a teacher, who has to diagnose students' errors, but it is not helpful for a student, who really shouldn't even imagine making such errors.

But the thinking demanded by the problem happens to be the way to answer JasonTurner! You need to ask yourself why he is doing each step, and whether it makes sense; and also to see that what he calls the wall is really the floor.
 
Dr.Peterson said:
That answer really doesn't need refutation. But you can refute it yourself.

JasonTurner calculated area rather than perimeter (as if the paper were to be used to cover the floor!); used centimeters, which wastes effort and invites error; and, at the end, found the perimeter of the paper which is utterly silly. Moreover, he didn't answer the question. This is not someone you need to pay attention to.

You were right that the student made the mistake of not converting to the same unit. There are other issues that have been rightly (and wrongly, at times) discussed. To me, the main point of the problem is to interpret how a border is used and how the dimensions of a room are stated, which is not really a math problem, but a test of background knowledge.

I dislike the problem particularly in that it forces you to think through wrong approaches to the problem, rather than helping you keep your attention on correct thinking. It may be a good exercise for a teacher, who has to diagnose students' errors, but it is not helpful for a student, who really shouldn't even imagine making such errors.

But the thinking demanded by the problem happens to be the way to answer JasonTurner! You need to ask yourself why he is doing each step, and whether it makes sense; and also to see that what he calls the wall is really the floor.
Click to expand...
Got it. Thank you Dr Peterson .
 
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