Math problems

[Ethereal]

The inspiration for this came up in another thread. I'll spare you the details except to say that another poster is going to attempt to solve a math problem that I devised. Everyone is free to contribute, but I would ask that you wait at least one hour AFTER I post the problem to post any solutions. If this proves amusing to the forum, I may post other math questions from time to time.

Question 1

An airplane company is designing a new jet. The jet's cabin is modeled as a cylinder with two openings at each end. The openings at each end of the cylinder are 8 feet across. The cylinder is 40 feet long. The company wants to use aluminum to fabricate the cabin based on this cylindrical model. How many square feet of aluminum does the company need to fabricate the cabin?

[RichardMZhlubb]

FYI, there is not enough information in this question to answer it.

[invictus]

The inspiration for this came up in another thread. I'll spare you the details except to say that another poster is going to attempt to solve a math problem that I devised. Everyone is free to contribute, but I would ask that you wait at least one hour AFTER I post the problem to post any solutions. If this proves amusing to the forum, I may post other math questions from time to time.

Question 1

An airplane company is designing a new jet. The jet's cabin is modeled as a cylinder with two openings at each end. The openings at each end of the cylinder are 8 feet across. The cylinder is 40 feet long. The company wants to use aluminum to fabricate the cabin based on this cylindrical model. How many square feet of aluminum does the company need to fabricate the cabin?

If I recall correctly than the radius is 4 feet times squared times pi which is 3.14 (I had to look up pi)... Which comes out to 2009.6 square feet...

Okay, so what did I get wrong and where?

[invictus]

Simpler than your problem but...

Two cars start at the same point and drive in the opposite direction. They drive 8 miles each and then both make a right turn and drive 6 miles each. How far apart are they?

[RichardMZhlubb]

If I recall correctly than the radius is 4 feet times squared times pi which is 3.14 (I had to look up pi)... Which comes out to 2009.6 square feet...

Okay, so what did I get wrong and where?

The ends of a cylinder "with two openings at each end" would look like this:



I'm sure that's not what he intended, but that's what the question says. As worded, you cannot answer the question without more information about the space between the two openings on each end.

[invictus]

The ends of a cylinder "with two openings at each end" would look like this:



I'm sure that's not what he intended, but that's what the question says. As worded, you cannot answer the question without more information about the space between the two openings on each end.

Okay I see. I'll have to look that up. The number did seem high.

[Ethereal]

FYI, there is not enough information in this question to answer it.

Try again.

[RichardMZhlubb]

Try again.

You can’t answer the question without knowing the diameter of the ends and you haven’t provided enough information to figure that out.

[Ethereal]

You can’t answer the question without knowing the diameter of the ends and you haven’t provided enough information to figure that out.

The openings at each end of the cylinder are 8 feet across.

[Ethereal]

The ends of a cylinder "with two openings at each end" would look like this:



I'm sure that's not what he intended, but that's what the question says. As worded, you cannot answer the question without more information about the space between the two openings on each end.

It's just a standard cylinder with two open ends. It would look like this:

31LvRtY22tL._AC_SX466_.jpg

The openings at each end are 8 feet across and the cylinder is 40 feet long.

That is all the information you need to calculate its surface area.