Confused about ratios: Math Destroyer Test 7 #11

[Wererew]

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Hello,

The question asks: ".. $1 is equal to 7 drachmas, and 5 drachmas is equal to 3 quilos. What is the ratio of dollars to quilos?"

Is it the same as if they were asking how many quilos there are in one dollar?

Answer: 21/5

1$ = 7D
5D = 3Q
multiplying the second equation by 7/5 we get: 1$=7D= (21/5)Q

I got to solving til this part, but when the question asks the ratio of dollars to quilos,
I put 1 : (21/5) and flipping it to come up with 5/21... I thought that ":" is the same as a fraction.. what is the mistake I am making?

Thanks so much

 

[MickeyMug]

Hi there!

I was having the same issue with that one problem, I think the wording of the question is a little misleading.
So here's how you should approach this question:
You know that $1 = 7D and 5D = 3Q
If you solved for D for the equation 5D = 3Q you would get D = (3/5)Q
Then you can substitute (3/5)Q for D => $ = 7[(3/5)Q] => $ = (21/5)Q
Then you divide Q from both sides and get $/Q = 21/5

Hope this helps!

 

[DAT Destroyer]

You got $1=(21/5)Q which is correct. The question is asking for the ratio of dollars to quilos ( $/Q)
Divide both sides by Q to get:
$/Q = 21/5

 

[Wererew]

Ohh I see it now! Thanks alot! 🙂

 

[DAT Destroyer]

Ohh I see it now! Thanks alot! 🙂

Always happy to help, if you have any more questions feel free to post.

Nancy