Q.

A manufacturer has 800 L of a 10% solution of acid. The range of 35% acid to be added to it is (a, b) such that the acid content in the resultant mixture will be more than 15% but less than 25%, then a+b= ________.


Ans.

(1400)

Let x L of 35% acid solution is added to the solution.

Total mixture=(x+800) L

According to question,

             35% of x+10% of 800>15% of (x+800)

and       35% of x+10% of 800<25% of (x+800)

∴  15100(800+x)<35100x+10100×800

and     25100(800+x)>35100x+10100×800

⇒  12000+15x<35x+8000  and  20000+25x>35x+8000

⇒  4000<20x  and  12000>10x

⇒  200<x  and  1200>x  i.e.,  200<x<1200

Thus,  a=200,  b=1200

Hence, a+b=200+1200=1400