Achemist has 300 grams of 20% hydrochloric acid solution. he wishes to drain some and replace it with an 80% solution so as to obtain a 25% solution. how many grams must he drain and replace with the 80% solution?

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The chemist has to drain 25 grams of the 20% hydrochloric acid solution and replace with the 80% solution

Solution:

Let us first set up a table and fill in the known values given

The table is attached below

Let "x" be the amount in grams for 20% acid solution

Let "y" be the amount in grams for 80% acid solution

From the given table, we can set up two equations

Sum of values of two acids = Value of mixture  

0.2x + 0.8y=75  

For convenience, we'll multiply the entire equation by 10,

2 x + 8 y = 750

x + 4y = 375 ------ eqn (1)  

Now, Sum of amounts of each acid = Amount of mixture  

x + y = 300 --------- eqn (2)

Subtracting equation (2) from (1),  

( + ) x + 4 y = 375

( − )  x +  y = 300

− − − − − − − −

( = ) 0 + 3y = 75  

Thus, 3y = 75

y = 25  

Substituting y = 25 in eqn (2),

x + 25  = 300

x = 300 – 25 = 275  

So, we have x = 275 and y = 25

Here "y = 25" represents amount in grams for 80% acid solution.

We can conclude that he has to drain 25 grams of the 20% acid solution.

derp.

Step-by-step explanation:

First guy wrong

answer:   28.56 feet (approx)

step-by-step explanation:

since, triangle abc has measure of angle c equal to 55 degrees, measure of angle abc equal to 90 degrees, and length of bc equal to 20 feet.

we have to find out the measurement of segment ab.

therefore, tan 55° =

but bc = 20 feet.

⇒ tan 55 ° =  

⇒ ab = 20 × tan 55 °

⇒ ab = 20 × 1.42814800674

⇒ ab = 28.5629601348   ≈ 28.56 feet