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Explain reasoning!

1.) If you make 20% more money than me, then I make 20% less than you.

2.)If I have an average of 60% before the final , then I must score 80% on the final in order to raise my average up to 70% to pass the this Math 75 class.

Respuesta :

Answer:

1.) Incorrect,

2.) Correct

Step-by-step explanation:

1.) Let x be the amount of money,

After increasing x by 20%,

New amount of money ( say y )= (100+20)% of x ( i.e. y is 20% more than x )

= 120 % of x

[tex]=\frac{120x}{100}[/tex]

⇒ y = 1.20x

[tex]\because \frac{y-x}{y}\times 100=\frac{ 1.20x-x}{1.20x}\times 100[/tex]

[tex]=\frac{0.2x}{1.2x}\times 100[/tex]

[tex]=\frac{20}{1.2}[/tex]

≈ 16.67%

Thus, x is approximately 16.67% less than y.

2.) First score = 60%,

Second score = x% ( let )

So, Average percentage score = [tex]\frac{60+x}{2}[/tex]

If [tex]\frac{60+x}{2}=70[/tex]

[tex]60+x=140\implies x = 80[/tex]

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