How many litres of water will have to be added to 600 litres of the 45% solution of acid so that the resulting mixture will contain more than 25%, but less than 30% acid content?
Let x litres of water may be added. Then,
25% of (600+x)<600×45100<30% of (600+x)
⇒600+x4<270<1800+3x10
⇒600+x4<270<1800+3x10>270
⇒600+x<1080 and 1800+3x>2700⇒300<x<480