Math Help

[AdaAda87]

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I need some help with these three math problems, I couldn't figure them out.

Kate has 6 diff books. Assuming order doesnt matter, how many ways can kate select from these 6 books, two different books?

Ans is 15 but why?

Sales reductions force a factory to cut back its output by 20%. By what percentage must the reduced sales be increased to allow production to be brought back to normal?

ANS 25 why?

The current sales price of a drill is 117 dollars. This is 30 dollars more than half the list price. At what discount is the drill being sold?

Ans 25.6%

Thanks in advance!

 

[klutzy1987]

I need some help with these three math problems, I couldn't figure them out.

Kate has 6 diff books. Assuming order doesnt matter, how many ways can kate select from these 6 books, two different books?

Ans is 15 but why?

Sales reductions force a factory to cut back its output by 20%. By what percentage must the reduced sales be increased to allow production to be brought back to normal?

ANS 25 why?

The current sales price of a drill is 117 dollars. This is 30 dollars more than half the list price. At what discount is the drill being sold?

Ans 25.6%

Thanks in advance!

1. 6c4 = 6!/((6-4)!4!)= 15

2.You need to go back from 80% to 100%. This is an increase of 20/80 or 25%

3.117-30=half the list price. The half list price=87$. Therefore the whole list price is 174$. If it is being sold for 117 dollars and list is 174 then 117/174=67.2% Therefore your discount is 32.8% not 25.6. I dont know how you got that answer.

 

[dvduplex]

3.117-30=half the list price. The half list price=87$. Therefore the whole list price is 174$. If it is being sold for 117 dollars and list is 174 then 117/174=67.2% Therefore your discount is 32.8% not 25.6. I dont know how you got that answer.

this is how I think they get 25.6%

117/2= 58.5, which is half the list price

58.5 x 2= 117, which is the whole list price

117+30= 147

147-117= 30

30/117= .256

.256 x 100%= 25.6%