can you please check to see it these are right

Question

anonymous · Answer

Question 7 



What is the perimeter of a regular pentagon with side length 8 cm?

40 cm

48 cm

32 cm

24 cm




Question 10 

What is the surface area of a cube with side length 9 km ?







Question 14 



What is the surface area of a rectangular prism with length 15 m, width 9 m, and height 6 m?

810 m2

450 m2

558 m2

279 m2




Question 16 



Which units are most appropriate for measuring the area of a desktop?

cubic inches

square inches

cubic miles

square miles



Question 31
If the length of each side of a cube is tripled, is the surface area tripled? Use an example to support your answer.

anonymous · Answer

7. 40 cm

10. 486 km^2

14. 558 m^2

16. square inches

31. No, it is multiplied with 9.
A cube has a side length of 2 cm. It has a surface area of 24 cm^2. When this side length is tripled, the side length is 6 cm. This has a surface area of 216 cm^2. See what factor causes this change in surface area by setting up the ratio of the new surface area to the original surface area.
216/24 = 9
Instead of being tripled, the surface area is multiplied with 9.

anonymous · Answer

did i get these right

aravindg · Answer

7.right

anonymous · Answer

and the others

ganeshie8 · Answer

all correct.

shane_b · Answer

7 is right...10 isn't though...and I haven't checked the others.

anonymous · Answer

what is 10

anonymous · Answer

is it 749

shane_b · Answer

Surface area of a cube is:$$A_{surface}=6a^2$$Since the length of each side is 9km, the area of each side is 81km^2.  Multiply that times 6 and you get 486km^2.

anonymous · Answer

opps 729

anonymous · Answer

thats what i said for number 10

shane_b · Answer

omg...I'm blind.

anonymous · Answer

lol

ganeshie8 · Answer

For 31 :
31. No, it is multiplied with 9.
A cube has a side length of 2 cm. It has a surface area of 24 cm^2. When this side length is tripled, the side length is 6 cm. This has a surface area of 216 cm^2. See what factor causes this change in surface area by setting up the ratio of the new surface area to the original surface area.
216/24 = 9
Instead of being tripled, the surface area is multiplied with 9.

anonymous · Answer

is that right???

ganeshie8 · Answer

its right.. they are asking for example only in the Q..

anonymous · Answer

ok so if turned this in i would get a 100 right

ganeshie8 · Answer

Yup you got 100 already..  from OS :)

for 31 : add below info aswell
A is proportional to L^2.  so if L triples, A become 9 times

shane_b · Answer

I agree that they are all correct...just looked at the others.

shane_b · Answer

including ganeshie8's correct to 31.

anonymous · Answer

ok you all helped me i would give you both best answer but i cant :(

shane_b · Answer

I didn't do anything...@ganeshie8 got this one.

anonymous · Answer

ok he will get it

anonymous · Answer

ok thanks everyone

ganeshie8 · Answer

Shane double confirmed me.. i already gave Best answer to yoyo... so cant give another :(

shane_b · Answer

I won't lose any sleep over OS points :)