Question

You have a 3.00mL of a 500 mg/dl urea standard. How much water must be added to produce a final concentration of 200mg/dl?

Answer 1

mg = ..milligrams?

dl =....got no clue lol

Answer 2

whats mg/dl mean?

Answer 3

milligrams per deciliter

Answer 4

i suspected as much... :)

Answer 5

3 mL = .03 decaliters...

Answer 6

500*.03 = 15

500(.03) + 0(w) = 200(.03 + w) I assume

Answer 7

500 = 6 + 20w

496 = 20w

24.8 = w

24.8 decaliters of water if I did it right :)

Answer 8

2480 mL of water sound right to you?

Answer 9

seems a little high, since the standard was only 3.00mL

Answer 10

i see an error..... I did 20 and not 200; dropped an important zero :)

Answer 11

500 = 6 + 200w

496 = 200w

496/200 = w

water = 2.48 dl which is 248 mL

Answer 12

..still off; i see another error :)

Answer 13

500*.03 = 15

15 = 6 + 200w

9 = 200w

9/200 = w

0.045 decaliters of water if I did it right this time...

w = 4.5 mL ....better?

Answer 14

that seems correct!

Answer 15

lol ..... gonna have to recall alot of prescriptions after that :)

Answer 16

i appreciate it!

Answer 17

may i ask how you got the 6, in 15 = 6 + 200w?

Answer 18

Let t be the amount of chemical. Then t/3.00 = 500 => t = 1500

t/x = 200
=> x = 1500/200 = 7.5 mL must be added

Answer 19

200*.03 = 6

Answer 20

No 3.5 must be added for total of 7.5

Answer 21

i figure we need a 200 solution that is a combonation of .03 and "water"

200(.03 + w) = 6 + 200w ..... not that the equation is right to begin with :)

Answer 22

Shoot 4.5 added to the original 3.0 to get 7.5

Answer 23

ivan..lol; was I right :)

Answer 24

yep both ways work, i appreciate the help!

Answer 25

This is why I suck on a test

Answer 26

the math I can do....sometimes, when the moon is full and the butterflies are dancing among the daisies that is :)

Answer 27

i've got a few more, i'll post questions, walking me through that made so much more sense

Answer 28

You must change mine to be kosher

t/(3.00+ x) = 1500 => .... x = 4.5

Answer 29

Or you could introduce let new amount_new = 3.00 + x

Then

t/amount_new = 200
or
Amount_new = 1500/200 =7.5 => x = 7.5 - 3.0 = 4.5

Answer 30

Thanks!