# Need to find the mistake

• May 12th 2012, 03:36 PM
nazz
Need to find the mistake
Given f = u.v/u+v

U= 8.8, v= 6.2 correct to 1 decimal place.

Find the upper and lower bound of F

Upper boundF= 8.85x6.25/8.75+6.15
lower bound F = 8.75x6.15/ 8.85+6.25

Second part of the question is find a mistake in the problem, I can't figure it out what it is?
• May 12th 2012, 04:27 PM
Wilmer
Re: Need to find the mistake
Quote:

Originally Posted by nazz
Given f = u.v/u+v

U= 8.8, v= 6.2 correct to 1 decimal place.

Find the upper and lower bound of F

Upper boundF= 8.85x6.25/8.75+6.15
lower bound F = 8.75x6.15/ 8.85+6.25

Second part of the question is find a mistake in the problem, I can't figure it out what it is?

Couple points: do not change a variable like f to F; use * as multiplication sign, not x.
And use brackets to be CLEAR:
Upper bound F= 8.85 * 6.25 / (8.75 + 6.15)
lower bound F = 8.75 * 6.15/ (8.85 + 6.25)

Your question is unclear; can you post the EXACT original problem?
If there's any "mistake", your 2 equations should be:
Upper bound F= 8.85 * 6.25 / (8.85 + 6.25)
lower bound F = 8.75 * 6.15/ (8.75 + 6.15)
I've never seen 2 different values for a variable in the same equation (Shake)
• May 12th 2012, 04:34 PM
nazz
Re: Need to find the mistake
Ok thanks for your comments, please read about upper and lower bounds!!!! Teacher said that there is a mistake in the layout of the question, it is from a book and i wrote it exactly as it is written? Any feedback without any lectures on how to write equations please?
• May 12th 2012, 04:45 PM
Moebius
Re: Need to find the mistake
I believe the mistake is, as Wilmer posted, that the denominators need to be swapped between the two functions. The equation for the upper bound is using the lower bound values in the denominator, and the equation for the lower bound has the upper bound values in its denominator.
• May 12th 2012, 06:53 PM
Wilmer
Re: Need to find the mistake
Quote:

Originally Posted by nazz
Any feedback without any lectures on how to write equations please?

No. Learn to write equations properly.
3x + 5 = 2x + 10
You can have ONLY one value for x, not two.
• May 13th 2012, 01:17 AM
nazz
Re: Need to find the mistake
Understand the subject
• May 13th 2012, 01:57 AM
nazz
Re: Need to find the mistake
We were told that there is a mistake in the actual question
And not the answer, we have to spot this mistake
• May 13th 2012, 06:18 AM
Wilmer
Re: Need to find the mistake
Quote:

Originally Posted by nazz
Given f = u.v/u+v

U= 8.8, v= 6.2 correct to 1 decimal place.

Find the upper and lower bound of F

Upper boundF= 8.85x6.25/8.75+6.15
lower bound F = 8.75x6.15/ 8.85+6.25

Second part of the question is find a mistake in the problem, I can't figure it out what it is?

I should let you mellow in your self-righteousness.
I quite understand upper and lower bounds.
YOU did not specify that this (I think) is your answer (not correct) to part one:
> Upper boundF= 8.85x6.25/8.75+6.15
> lower bound F = 8.75x6.15/ 8.85+6.25
It appears that it is part of the question.
So the wrong denominators used is YOUR mistake, not the mistake in part one.

The mistakeS in the problem, the problem being:
> Given f = u.v/u+v
> U= 8.8, v= 6.2 correct to 1 decimal place.
> Find the upper and lower bound of F
are:
1: use of u and U to represent same variable
2: use of f and F to represent same variable
3: denominator not bracketed as (u+v), meaning f = (u.v/u) + v
and the one the teacher is probably expecting:
> Find the upper and lower bound of F
should be:
Find the upper and lower bound of F to 1 decimal place

Have a good day.
• May 13th 2012, 08:45 AM
nazz
Re: Need to find the mistake
Thanks Wilmer, mighty nice of ypu