Net resistance of 100, 250 and 400 ohm resistors in parallel

[kllindsey]

Question: Determine the net resistance of 100 ohms, 250 ohms and 400 ohms connected in a parallel.

I have no clue how to figure this out. I have read and reread the section in my book and it is not helping. Please help.

 

[Feldoh]

Well what have you tried so far?

 

[kllindsey]

1/Rp = 1/100 + 1/250 + 1/400

I know the answer is:

1/Rp = 60 + 24 + 15/6000 ohms
Rp = 6000 ohms/99 = 61 ohms

I just have no clue where these numbers are coming from!

 

[Studiot]

Well I haven't a clue how you got from your formula to your second line.

I agree that your answer of 61 is close enough though.

Can you not do the arithemetic involved in your first line?

 

[Feldoh]

Your answer and the books answer are the same. They just multiply the fractions so there is a common denominator (However odd that denominator is)