cross multiplying question.

[joonkimdds]

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This is a problem from Kaplan blue book.

(25/8)inch = 125 feet
? inch square = 20feet x 20feet

according to the book they use
(25/8) =125
? = 20

then as soon as they get ? , they square it to get the answer, which is 1/4

if i use that mathod i get the same answer
but can i use this mathod below?
(25/8) = 125
? = 20square (therefore 400)

if i use this, i get 10.
how are they different?

 

[Flipper405]

This is a problem from Kaplan blue book.

(25/8)inch = 125 feet
? inch square = 20feet x 20feet

according to the book they use
(25/8) =125
? = 20

then as soon as they get ? , they square it to get the answer, which is 1/4

if i use that mathod i get the same answer
but can i use this mathod below?
(25/8) = 125
? = 20square (therefore 400)

if i use this, i get 10.
how are they different?

I don't even understand the question. How is 25/8 of an inch = 125 feet?

Are they saying if 25/8 inch = 125 feet, then how many square inches is 20 square feet?

 

[joonkimdds]

I don't even understand the question. How is 25/8 of an inch = 125 feet?

Are they saying if 25/8 inch = 125 feet, then how many square inches is 20 square feet?

,.

 

[ryche22]

write the entire question verbatim. dont paraphrase.

 

[Flipper405]

write the entire question verbatim. dont paraphrase.

Please. That would help us help you. Help me.. help you. 😎

 

[joonkimdds]

Please. That would help us help you. Help me.. help you. 😎

an architect draws a blueprint so that 25/8 inches represents 125 feet. how many square inches are used to represent the area of a room 20 feet by 20 feet?

 

[paulee1983]

an architect draws a blueprint so that 25/8 inches represents 125 feet. how many square inches are used to represent the area of a room 20 feet by 20 feet?

if you use your method,

25/(8x)=125/(400), x is actual area in feet

notice that 125 is ft but 400 is sq. ft, so they are different
to make it works, you should square both sides:

(25/(8x))^2= (125^2)/400

so all numbers are in sq.ft. It makes the thing more complicate
but you still get x=1/2, thus x^2=1/4 for the answer.

 

[isd121]

25/8 inches = 125 feet

so, 1 foot = (25/8)/125 = 1/40 inches

20 feet = (1/40)*20 = 1/2 inch

Area of the room is 20 * 20 sq feet
but on the blueprint it is (1/2)*(1/2) = 1/4 sq inch

🙂

an architect draws a blueprint so that 25/8 inches represents 125 feet. how many square inches are used to represent the area of a room 20 feet by 20 feet?