Destroyer Math Question

[Illfavor]

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"While touring Europe, Alfred finds that $1=7drachmas and 5 drachmas=3 quills. What's the ratio of dollars to quills?"

I set it up as $5=35 drachmas=21 quills. Is that not correct? Seems to me the ratio of dollars to quills would then be 5:21. Another way to look at it is that 1 drachma = $.14 and .6 quills, so how could the ratio of dollars to quills be greater than one? Destroyer says it's 5/21. EDIT: Destroyer says it's 21/5. Why? Thanks.

 

[Glimmer1991]

"While touring Europe, Alfred finds that $1=7drachmas and 5 drachmas=3 quills. What's the ratio of dollars to quills?"

I set it up as $5=35 drachmas=21 quills. Is that not correct? Seems to me the ratio of dollars to quills would then be 5:21. Another way to look at it is that 1 drachma = $.14 and .6 quills, so how could the ratio of dollars to quills be greater than one? Destroyer says it's 5/21. Thanks.

Hey! Haven't you answered your own question? 5 bucks is 35 drachmas is 21 quills. That's literally 5/21! I think maybe you've been studying for too long tonight. 😛

 

[virajpatel]

Might want to take a break with the studying lol you seem to have answered your own question.

 

[Illfavor]

Yea...maybe...yea.😴

 

[kyeongkong]

Doesn't Destroyer answer say it is (E)21/5?

 

[Illfavor]

Doesn't Destroyer answer say it is (E)21/5?

Yea! So why is that right? I'll edit my original post.

 

[kyeongkong]

So when a question is asking you "ratio of X to Y" then we usually simply just do x/y. So when I solved that question I simply divided 5/21 and put that as an answer. But when one say "ratio of dollar to quill" it means find a number that has unit of quill/dollar. So from the question, we are given 7d/$, and 3q/5d. So if we just multiply those numbers (with units):

(7*3)/5 (q/$) = 21/5 q/$.

This might seem a bit odd, but if you see other question, it might become clearer. So from the same test, question #24, it is asking you to find "ratio of areas of larger square to smaller square"

So using same logic from above, our answer should have unit of "Small square / Larger square"

When we find areas, Area of Large square = x^2, Area of small square = x^2/2

we can just use simple do x^2/(x^2/2) and get answer 2, but to make my point clear and help better understand question #11,

here, I can rewrite areas with proper units (I neglected unit cm^2 for cleanness):

x^2 per large square (x^2/LS)
X^2/2 per small square ((x^2/2)/SS)

So we want our final number to have unit of SS/LS,

(x^2/LS)/((x^2/2)/SS) = 2 SS/LS

... Hope that was clear enough.

 

[mostprecious]

DAT Destroyer is wrong. I myself was puzzled. It should be 5/21. Ratio of dollars to quills is 5/21. Ratio of quills to dollars is 21/5. It's reversed by mistake, I guess. All other problems in the DAT Destroyer that are similar to this problem seem to be fine, but this one doesn't agree.

 

[NewBee12]

the answer is 21/5

1$ = 7D and 5D = 3Q then D=3Q/5

1$= 7x3Q/5 =21Q/5 then 5$ = 21Q

the question is asking for $/Q then $/Q = 21/5

if ab = cd then a/c = d/b NOT b/d

hope this clarifies things

 

[gn4]

Can somebody tell me which destroyer question this is? Is this math or dat destroyer qr section?

 

[NewBee12]

Math destroyer . Don't remember the exact rest.

 

[gn4]

ok. cool. I can find it. Thanks.

 

[Illfavor]

I think I'm just struggling conceptually. $5=21Q, so $/Q =21/5. The currency values are like additional variables, so I can't just think of them as isolated values. Oook 👍

 

[We Are PS]

ok. cool. I can find it. Thanks.

Don't know if you found it or not but it's question 11 Practice Test 7.

 

[gn4]

Don't know if you found it or not but it's question 11 Practice Test 7.

Oh yes I did. Thank you.