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How many litres of water will have to be added to 1125 litres of the 45% solution of acid so that the resulting mixture will contain more than 25% but less than 30% acid content?

Q13.    How many litres of water will have to be added to 1125 litres of the 45% solution of acid so that the resulting mixture will contain more than 25% but less than 30% acid content?

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Let  x  litres of water is required to be added.

Total mixture = (x+1125) litres 

It is evident that amount of acid contained in the resulting mixture is 45% of 1125 litres.

The resulting mixture contain  more than 25 % but less than 30%  acid.

\therefore \, 30\%\, of\, (1125+x) > 45\%\, of\, (1125)                    and       25\%\, of\, (1125+x)< 45\%\, of\, 1125  

\Rightarrow \, 30\%\, of\, (1125+x) > 45\%\, of\, (1125)                  and       25\%\, of\, (1125+x)< 45\%\, of\, 1125

\Rightarrow \, \frac{30}{100}(1125+x)> \frac{45}{100} (1125)                                 \Rightarrow \, (\frac{25}{100}) (1125+x)< \frac{45}{100} (1125)

\Rightarrow \, 30\times 1125+30x> 45\times (1125)                              \Rightarrow \, 25 (1125+x)< 45(1125)

\Rightarrow \, 30x> (45-30)\times (1125)                                            \Rightarrow \, 25 x< (45-25)1125

\Rightarrow \, 30x> (15)\times (1125)                                                        \Rightarrow \, 25 x< (20)1125

\Rightarrow \, x> \frac{15\times 1125}{30}                                                                   \Rightarrow \, x< \frac{20\times 1125}{25}

\Rightarrow \, x> 562.5                                                                              \Rightarrow \, x< 900

Thus, the number of litres water that is to be added will have to be more than 562.5 and less than 900 litres.

 

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