Complete A Table By Evaluation

[nycmathguy]

Homework Statement

Complete a table by evaluation.

Relevant Equations

y = 10,370/(x^2)

The resistance y (in ohms) of 1000 feet
of solid copper wire at 68 degrees Fahrenheit is y = 10,370/(x^2) where x is the diameter of the wire in mils (0.001 inch).

Complete the table.

x...60 70 80 90 100
y...

Solution:

Let x = 60

y = 10,370/(60)^2

y = 10,370/3600

y = 2.8805555556

This decimal cannot be the answer for y to be placed in the table above, right?

I need to know if this is right before moving on.

 

[Frabjous]

Why do you think it is wrong?

 

[nycmathguy]

Why do you think it is wrong?

I just feel the number should be rounded off at least to two decimal places. You say?

 

[Frabjous]

It’s hard to tell where to round it. 10370 has five digits, so you should not have more than 4 decimal places. Teachers can be retentive about these things, but personally I would round to 2 or 3 decimal places.

 

[nycmathguy]

It’s hard to tell where to round it. 10370 has five digits, so you should not have more than 4 decimal places. Teachers can be retentive about these things, but personally I would round to 2 or 3 decimal places.

Ok. Will do.

 

[Frabjous]

You might want to read the wikipedia page on significant figures
https://en.wikipedia.org/wiki/Significant_figures