Posted by madad on .
A photo width of 8cm, length of 14cm .if the perameter of photo is increased by 5o % , which dimension is for new perimeter.
options are:
16cm by 28cm
12cm by 21cm
4cm by7cm
8cm by28 cm
i chose the first option cuz it increased 50.but i ma not sure if i am right.

Math 
Ms. Sue,
Present perimeter: 16 + 28 = 44
44 * 1.5 = 66 = new perimeter
The perimeter you chose is 32 + 56 = 88
Check out the other options. Which produces a perimeter of 66 cm? 
Math 
hiba,
8cm by 28 cm ?
I am confused . Geometery is not my thing . 
Math 
Ms. Sue,
P = 2L + 2W
Present perimeter:
P = 2(8) + 2(14)
P = 16 + 28
P = 44 
Math 
hiba,
it make sense so , just apply the Perameter formula and put the valuse so answers is 44 then 44*1.5 = 66.
But How i have deal with increased 50% deminsion thing .
please can you simplfy this . 
Math 
Ms. Sue,
Use trial and error.
Using your choices, figure out the perimeter for each set of dimensions.
P = 2L + 2W
Which produces a perimeter of 66? 
Math 
hiba,
12cm by 21cm = 2*33= 66
?? 
Math 
Ms. Sue,
Let's check it out.
P = 2(21) + 2 (12)
P = 42 + 24
P = 66
Right! 
Math 
hiba,
Thanks.

Math 
Ms. Sue,
You're welcome.

Math 
bede,
there is options like 4cm by 7cm,8cm by 28cm 12cm by21cm16cm by28cm.how do I go to this options from 66.