2016 math destroyer test 7 #11

[gangazi]

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For question 11 Math destroyer test 7 (2016), What is the ratio of dollars to quilos?

I got 1 dollar = (21/5)quilo

My question is: when I see the questions lke "what is the ratio of x to y" I try to get the numerical answer by doing x/y. In this came, I did ratio of dollar to quilo = (1) / [(21/5)] and got 21/5

On the same test number 24, What is the ratio of the areas of the larger square to the smaller square?
I just plugged in number and got the areas of 16 and 8... so I did ratio of Large : Small square = 16/8 and got 2... which is the correct answer.
Can someone explain whats the difference between the two?
Thank you

 

[Roy Williams]

For question 11 Math destroyer test 7 (2016), What is the ratio of dollars to quilos?

I got 1 dollar = (21/5)quilo

My question is: when I see the questions lke "what is the ratio of x to y" I try to get the numerical answer by doing x/y. In this came, I did ratio of dollar to quilo = (1) / [(21/5)] and got 21/5

On the same test number 24, What is the ratio of the areas of the larger square to the smaller square?
I just plugged in number and got the areas of 16 and 8... so I did ratio of Large : Small square = 16/8 and got 2... which is the correct answer.
Can someone explain whats the difference between the two?
Thank you

What is a quilo? And isn't (1)/(21/5) = 5/21? Not 21/5?

 

[DAT Destroyer]

For question 11 Math destroyer test 7 (2016), What is the ratio of dollars to quilos?

I got 1 dollar = (21/5)quilo

My question is: when I see the questions lke "what is the ratio of x to y" I try to get the numerical answer by doing x/y. In this came, I did ratio of dollar to quilo = (1) / [(21/5)] and got 21/5

On the same test number 24, What is the ratio of the areas of the larger square to the smaller square?
I just plugged in number and got the areas of 16 and 8... so I did ratio of Large : Small square = 16/8 and got 2... which is the correct answer.
Can someone explain whats the difference between the two?
Thank you

The word Ratio means the quotient of 2 things. For example the ratio of a to be is simply a/b.
For your first question here's an example:
Let's say: ab = cd. What's the ratio of a to c? the answer is a/c = d/b

For your second question the answer is straight forward. The ratio of the area of the larger square to the smaller square is simply:
Area of larger square/Area of the smaller square.

here's another example: Circle A has radius 2 and Circle B had radius 4. What's the ratio of the areas of the larger circle to the smaller circle?

Answer: Area of the larger circle/Area of the smaller circle = 4

 

[gangazi]

I just checked the solution and it says 1 dollar = 21/5Quilo and the ratio of dollars to quilo is 21/5

shouldnt ratio be 5/21?

 

[gangazi]

What is a quilo? And isn't (1)/(21/5) = 5/21? Not 21/5?

Yes you are right but the answer choice says that the ratio of dollars to quilos is 21/5

 

[Roy Williams]

Yes you are right but the answer choice says that the ratio of dollars to quilos is 21/5

What's the actual question? Word for word?

 

[FutureDent20]

For question 11 Math destroyer test 7 (2016), What is the ratio of dollars to quilos?

I got 1 dollar = (21/5)quilo

My question is: when I see the questions lke "what is the ratio of x to y" I try to get the numerical answer by doing x/y. In this came, I did ratio of dollar to quilo = (1) / [(21/5)] and got 21/5

On the same test number 24, What is the ratio of the areas of the larger square to the smaller square?
I just plugged in number and got the areas of 16 and 8... so I did ratio of Large : Small square = 16/8 and got 2... which is the correct answer.
Can someone explain whats the difference between the two?
Thank you

Solve is as if you are doing G-chem problem:

1 dollar x 7 drachmas/1 dollar x 3 quilos/5 drachmas = 21/5
Which means 1$ = 21/5 Quilos

 

[gangazi]

Solve is as if you are doing G-chem problem:

1 dollar x 7 drachmas/1 dollar x 3 quilos/5 drachmas = 21/5
Which means 1$ = 21/5 Quilos

so 5$ = 21quilos
and ratio of dollar to quilo = 5/21 in my mind..

 

[FutureDent20]

so 5$ = 21quilos
and ratio of dollar to quilo = 5/21 in my mind..

Exactly. $5 = 21 Q , $10 is 42Q, but 1$ dollar is 21/5Q.

Here an example: 1L = 1000mL and 2mL = 2 cm^3. whats the ratio of L to Cm^3. Think of 1L as $, 10000ml as 7D, 2mL as 5D, and 2cm^3 as Q. solving that you see the ratio as being 1L = 1000 cm^3/1

If you apply your case, you are saying 1L = 1/1000 cm^3 which is 0.001 cm^3 and we know that's not true. Hope it's clear now

 

[Don Kim]

1kg = 1000g. Ratio of kg to g is not 1/1000 because that would mean gram is inherently 1000 times kg, which makes no sense. To make it easy, treat the units like variables. So divide both sides by g. 1kg/g = 1000. This makes more sense since 1kg is 1000 times bigger than g.