
Let amount of water is added = x litre
Given solution is 1125 litre
Percentage of acid in solution = 45%
So percentage of water in solution = 55%
Case 1. Resulting mixture will contain more than 25% acid
x + 1125*55% = (x + 1125)*75%
=> x + (1125*55)/100 =(x + 1125)*75/100
=> 100x + 1125*55 =(x + 1125)*75
=> 100x + 1125*55 = 75x + 1125*75
=> 100x - 75x = 1125*75 - 1125*55
=> 25x = 1125*(75-55)
=> 25x = 1125*20
=> x = (1125*20)/25
=> x = (1125*4)/5
=> x = 225*4
=> x = 900
Case 2. Resulting mixture will contain more than 30% acid
x + 1125*55% = (x + 1125)*7%
=> x + (1125*55)/100 =(x + 1125)*70/100
=> 100x + 1125*55 =(x + 1125)*70
=> 100x + 1125*55 = 70x + 1125*70
=> 100x - 70x = 1125*70 - 1125*55
=> 30x = 1125*(70-55)
=> 30x = 1125*15
=> x = (1125*15)/30
=> x = (1125*5)/10
=> x = (1125)/2
=> x = 562.5
So water is added between 562.5 litre to 900 litre