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A nurse mixes 50 cc of a 60% saline solution with a 20% saline solution to produce a 28% saline solution. How much of the 20% solution should he use?

Sagot :

Answer:

  • 200 cc

Step-by-step explanation:

Let x be the added 20% solution.

The salt content is same:

  • 50*0.6 + x*0.2 = 0.28*(x + 50)
  • 30 + 0.2x = 0.28x + 14
  • 0.28x - 0.2x = 30 - 14
  • 0.08x = 16
  • x = 16/0.08
  • x = 200

Let added amount be y .

  • The salt remains same

[tex]\\ \tt\Rrightarrow 50(0.6)+0.2y=0.28(y+50)[/tex]

[tex]\\ \tt\Rrightarrow 0.2y+30=0.28y+14[/tex]

[tex]\\ \tt\Rrightarrow 0.2y-0.28y=14-30[/tex]

[tex]\\ \tt\Rrightarrow -0.08y=-16[/tex]

[tex]\\ \tt\Rrightarrow 0.08y=16[/tex]

[tex]\\ \tt\Rrightarrow y=\dfrac{16}{0.08}[/tex]

[tex]\\ \tt\Rrightarrow y=200[/tex]