Question

Area of a rectangle is 336 m^2. Ratio of Width and Length is 3:7.
Find Perimeter

Answer 1

I know that Area = W x L and Perimeter = 2 ( W+ L ) and it has something to do with cross multiply possibly.

Answer 2

sorry I couldn't post because the chat rooms obscured the post box.
I'll have to split the posts
Let x by measure of length + width

Answer 3

So perimeter is 2x

Answer 4

yes

Answer 5

\[\frac{ 336 }{ x } = \frac{ 3 }{ 7 }\]
is all i got in my head right now

Answer 6

which doesnt make sense

Answer 7

no it doesn't best to do it this way
as width:length = 3:7 we can write width = 0.3 x and length = 0.7x
do you follow that?

Answer 8

i dunno why it's .3 and .7

Answer 9

3 :7 means 3/10 for width and 7/10 for length ( 3+7 = 10)

Answer 10

alright how do we connect that to the area

Answer 11

area = w*l = 0.3x * 0.7x = 336
now solve for x

Answer 12

0.21x = 336
x = ?

Answer 13

my teacher says we can just do 3x and 7x

Answer 14

so that would be 21x

Answer 15

so x would be 16

Answer 16

for .21x = 336 that woukld be like 1600

Answer 17

no that would make the perimeter = 32 and the area would not come back to 336

Answer 18

wait x times x is x square right

Answer 19

right

Answer 20

sorry - my mistake

Answer 21

so x^2 = 1600
and x = 40

Answer 22

then width is .3 x so it would be .3 times 40 and same with the length

Answer 23

width would be 12 and length would be 0.7*40 = 28
and 12 8 28 = 336
so it works back ok

Answer 24

* 12 * 28

Answer 25

so the perimeter = 2x = 2*40

Answer 26

so perimeter is 80

Answer 27

right

Answer 28

yay thanks

Answer 29

yw