+0  
 
+5
708
3
avatar+111 

At a competition you need to finish 10 questions.

For every correct question you get 10 points and for every incorrect question you lose 3 points.

To  get an award you need 51 points min. How many (minimal) correct awnsers do you need to get an award.

(I think that it is 7 but they say that it is not correct)

 

AWNSER THIS FAST!

 Dec 16, 2014

Best Answer 

 #1
avatar+129899 
+10

Let x be the  number of questions answered correctly.....then, (10-x ) are the number answered incorrectly......and the questions answered correctly times their point value (10) plus the questions answered incorrectly times their point value (-3) must be greater or equal to 51

10x  + (-3)(10-x) ≥ 51   simplify

10x - 30 + 3x ≥ 51   combine like terms

13x  - 30 ≥ 51   add 30 to both sides

13x ≥ 81    divide both sides by 13

x ≥ about 6.2   → 7

Mmmm.....I get the same answer you did.....if we only answered 6 qusetions correctly that would be 6(10)- 3(4)  = 48 points.......and that's not enough !!

 

 

Maybe someome else sees something I'm missing???

 Dec 16, 2014
 #1
avatar+129899 
+10
Best Answer

Let x be the  number of questions answered correctly.....then, (10-x ) are the number answered incorrectly......and the questions answered correctly times their point value (10) plus the questions answered incorrectly times their point value (-3) must be greater or equal to 51

10x  + (-3)(10-x) ≥ 51   simplify

10x - 30 + 3x ≥ 51   combine like terms

13x  - 30 ≥ 51   add 30 to both sides

13x ≥ 81    divide both sides by 13

x ≥ about 6.2   → 7

Mmmm.....I get the same answer you did.....if we only answered 6 qusetions correctly that would be 6(10)- 3(4)  = 48 points.......and that's not enough !!

 

 

Maybe someome else sees something I'm missing???

CPhill Dec 16, 2014
 #2
avatar+111 
+5

Thanks. I got the awnser like this:

$${\mathtt{x}} = {\mathtt{10}}$$

$${\mathtt{y}} = {\mathtt{3}}$$

$${f}{\left({\mathtt{a}}\right)} = {\mathtt{xa}}{\mathtt{\,\small\textbf+\,}}{y}{\left({\mathtt{10}}{\mathtt{\,-\,}}{\mathtt{a}}\right)}$$

$${f}{\left({\mathtt{6}}\right)} = {\mathtt{48}}$$

$${f}{\left({\mathtt{7}}\right)} = {\mathtt{61}}$$

 Dec 16, 2014
 #3
avatar+129899 
+5

Yeah.....what you have done is pretty much the same as I have done.......sorry, unless there's something I don't see, that's all I've got !!!!

 

 Dec 16, 2014

0 Online Users