These questions are pertaining to College Algebra

Question

1) Troy wishes to strengthen a mixture that is 10% muratic acid to one that is 30% muratic acid. How much pure muratic acid should be added to 12 liters of the 10% mixture?

 

2) A boat travels upriver to a landing and then returns to its starting point. The trip upriver takes 1.2 hour, and the trip back takes .9 hour. If the average speed on the return trip is 5 mph faster than on the trip upriver, what is the boat's speed upriver.

Answer 1

 

                                liters sol'n      % muratic acidl             total liters 

 

10%                            12                 0.1                               (0.1) (12)

 

100%                            x                  1                                  (x)(1)

 

30%  mix                    12+x              0.3                            (12+x)(0.3)

 

 

From the last column, you get the equation

 

(0.1)(12) +x=0.3(12+x)

 

1.2 + x =3.6 +0.3x

 

x -0.3x = 3.6-1.2

 

0.7x = 2.4

 

x = 2.4 /0.7

 

x = 3.42

 

3.42 liter of pure acid should be added