How many Turns of cable: A full real of cable has a diameter of 60 inches. A job requires 314 feet of cable...

[KLL]

I can't seem to figure this question out.

A full real of cable has a diameter of 60 inches. A job requires 314 feet of cable. How many turns of cable should be taken off the reel? The answer is 20 turns, but I can't seem to figure out how to get 20.

 

[stapel]

A full real of cable has a diameter of 60 inches. A job requires 314 feet of cable. How many turns of cable should be taken off the reel? The answer is 20 turns, but I can't seem to figure out how to get 20.

What formula(s) or method(s) have you been given for this sort of exercise. ("The answer" will vary with the reality / complexity of the formula you're supposed to use.)

When you reply, please include a clear listing of your thoughts and efforts so far. Thank you!

 

[khansaheb]

I can't seem to figure this question out.

A full reel of cable has a diameter of 60 inches. A job requires 314 feet of cable. How many turns of cable should be taken off the reel? The answer is 20 turns, but I can't seem to figure out how to get 20.

Hint:

π ≈ 3.14159

 

[Dr.Peterson]

I can't seem to figure this question out.

A full [reel] of cable has a diameter of 60 inches. A job requires 314 feet of cable. How many turns of cable should be taken off the reel? The answer is 20 turns, but I can't seem to figure out how to get 20.

How long is one turn around the reel (in feet)? How many of those are needed to get 314 feet?

(I suspect that if you had written out what you tried, as we ask you to do, you might have caught your own error.)

 

[The Highlander]

I can't seem to figure this question out.

A full real of cable has a diameter of 60 inches. A job requires 314 feet of cable. How many turns of cable should be taken off the reel? The answer is 20 turns, but I can't seem to figure out how to get 20.

Hint:

π ≈ 3.14159

Don't use "π ≈ 3.14159" (as suggested above).

Instead, use: π ≈ 3.14 (an approximation that you have probably already been given?) ?

 

[Dr.Peterson]

Don't use "π ≈ 3.14159" (as suggested above).

Instead, use: π ≈ 3.14 (an approximation that you have probably already been given?) ?

There's really nothing wrong in using the more exact value for pi. (I myself used the [imath]\pi[/imath] button on the calculator.) You just have to do some obvious rounding on the final answer. (And that is in fact a more realistic problem, since rounding is almost always needed in real life.)

But it does seem likely that this class is taught to use the two-decimal-place approximation (which is commonly taught when calculators are not allowed, or before they existed); and in that case, of course, you should do what you are told.

 

[The Highlander]

There's really nothing wrong in using the more exact value for pi. (I myself used the [imath]\pi[/imath] button on the calculator.) You just have to do some obvious rounding on the final answer. (And that is in fact a more realistic problem, since rounding is almost always needed in real life.)

But it does seem likely that this class is taught to use the two-decimal-place approximation (which is commonly taught when calculators are not allowed, or before they existed); and in that case, of course, you should do what you are told.

Indeed, but in this case, using 3.14 gets the exact answer s/he's after.

(The 'clue' is in the "314 feet" specified in the question.)

 

[khansaheb]

I can't seem to figure this question out.

A full real of cable has a diameter of 60 inches. A job requires 314 feet of cable. How many turns of cable should be taken off the reel? The answer is 20 turns, but I can't seem to figure out how to get 20.

Did you figure out the way to get 20?

 

[Dr.Peterson]

Did you figure out the way to get 20?

Probably. Somebody asked the same question, showing a little work, an hour after asking us, and eventually seems to have solved it:

Calculating Cable Turns for a Job

Hello, I'm trying to help my kiddo with some math, and unfortunately this is stumping me. A full reel of cable has a diameter of 60 inches. A job requires 314 feet of cable. How many turns of cable should be taken off the the reel? The answer is 20 turns, but I can't seem to figure out how...

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But it would be nice if they'd interact with us, to bring a little closure.