Please check my answer for physics homework?

Question

A farmer measures the perimeter of a rectangular field. The length of each long side of the rectangle is found to be 40.48 m, and the length of each short side is found to be 13.5 m. What is the perimeter of the field?

I get 108 m every time, 3 significant figures, but it says it's wrong, please help

Answer 1

Simple exact answer is in form of points, and your calculator or system is giving the answer by rounding up. That's why u r confused.  

Answer 2

The perimeter of any rectangle is the sum of the lengths of all four sides

= 2 * 40.48 + 2 * 13.5

= 107.96 m

If the question asks for the answer "to 3 significant figures" then your answer IS correct and you should bring this to the attention of your teacher.  However, if it doesn't, you should always give the full answer - certainly to the same accuracy (number of decimal places) as the measurements given.

If your calculator / computer gives the answer 108 and you don't know why, it means it is set to round to 0 decimal places.  If you're using Microsoft Excel, this can be changed by clicking on the answer and then clicking Format > Cells > Number tab and then under Category, selecting "General", or "Number" and setting the decimal places to 2 (or more).

Hope this helps

Answer 3

I get the same:

2 * 40.48 = 80.96 m

2 * 13.5 = 27 m

80.96 + 27 = 107.96, round to 108

Even if they want you to round before multiplying, the result is the same:

2 * 40 = 80

2 * 14 = 28

80 + 28 = 108

As a 25+ year former tech writer, I can verify that sometimes the book is wrong :-).