a tank contains 100 gal of water. brine enters the tank at the rate of 3 gpm. the mixture, thoroughly stirred, leaves the tank at the rate of 2 gpm. if the concentration of the brine at the end of 20 minutes is to be 2 lb/gal, what should be the concentration of the brine entering the tank?

Question

lgbasallote · Answer

@amistre64 would you happen to know this cheese?

amistre64 · Answer

i think i recall it

lgbasallote · Answer

yay!

amistre64 · Answer

in-out = total amount that stays right?

lgbasallote · Answer

i believe so?

zepp · Answer

42.

lgbasallote · Answer

input - output = accumulation

lgbasallote · Answer

does that mean same thing?

amistre64 · Answer

yes

lgbasallote · Answer

i see i see

amistre64 · Answer

how do we calculate salinity?

amistre64 · Answer

is the brine 100% coming in?

lgbasallote · Answer

what does salinity mean?

amistre64 · Answer

brine is salt water; salt is a saline solution ....

lgbasallote · Answer

well the amt of brine coming in is represented by c1

the amt of water coming in is r1

lgbasallote · Answer

so c1 is 100% salt i believe

amistre64 · Answer

you have lbs/gal to figure out, but i dont see where you can determine how many lbs there is coming and going to start of with

anonymous · Answer

See this http://tutorial.math.lamar.edu/Classes/DE/Modeling.aspx

lgbasallote · Answer

here is the formula
$$\large r_1 c_1 - r_2 [\frac{Q}{V_o + (r_1 - r_2)t}] = \frac{dQ}{dt}$$

amistre64 · Answer

after 20 minutes tho, i would assume there is about 120 gallons in the tank; but i cant see a way of calculating lbs to gallons without knowing the ratio of the incoming brine

lgbasallote · Answer

i remember my teacher doing something like linear DE...does that help?

amistre64 · Answer

it might, but doesnt jog any memories :)

at any rate, i have to get back to pulling files for statistical analysises.  Good luck :)

lgbasallote · Answer

uhhmm okay..good luck to you too :)

lgbasallote · Answer

well i guess no one can solve this here.....