Question

A carpenter was told to make a desk with the dimensions of the top 50units by 40units but the carpenter actually made the desk top 60units by 35units, calculate the percentage error of:

-the length and width or the desk top
-the area of the desk top

Answer 1

I don't remember any shortcuts, so I'll just do it the long way.

Answer 2

First let's find the % error for the length of top:
50 -> 100%
60 -> x%
x = 6000/50 = 120%
SO he was off by 20% for length of top

Answer 3

40 -> 100%
35 -> x%
x = 3500/40 = 87.5%
So he was off by 12.5% this time

Answer 4

Finally the area.. originally the area was meant to be:
50*40=2000
But it turned out to be:
60*35=2100

Answer 5

So again:
2000 -> 100%
2100 -> x%
x = 210000/2000 = 210/2 = 105%, so he was off by 5%

Answer 6

does that make sense?

Answer 7

actually it doesn't even matter whether you take the desired value to be 100% and the actual value to be x%, or the other way around.

Answer 8

Because one way you'll get something like 105 and 100, the other way you'll get 100 and 95

Answer 9

yeah well i get it :) thanks :D

Answer 10

The difference is still 5

Answer 11

right, great!

Answer 12

Ohh I just figured out another way.. look it's cool.
Remember we assumed both length and width were 100%?

Answer 13

Then we got 120 and 87.5%

Answer 14

So originally, for area you had:
100*100 = 10,000%
then
120*87.5 = 10,500%
hmm that' still long.. lol ignore it

Answer 15

cuz then you'll have to figure out how much percent of 10,000 is 10,500

Answer 16

yeah lol :P