Question

Wesley has to gift wrap all the surfaces of the poster tube shown below.



What is the area of the gift wrapping paper that Wesley will need?

138.2 square inches

135.1 square inches

540.4 square inches

276.6 square inches

Answer 1

You want to use the surface area formula to figure out how much material is needed.
\[\large SA = 2 \pi r^2 + 2\pi rh\]

Answer 2

ooh okay

Answer 3

r = d/2
d = 2 in.

Answer 4

the radius is 1 right? or no

Answer 5

yes

Answer 6

So

Answer 7

okay I got 18.9 for the SA

Answer 8

hmm...
We found that r = d/2,so r = 1

and the height = 43 in. (long side)

Answer 9

oh okay give me a sec

Answer 10

\[\large SA = 2 \pi (\color{blue}1)^2 + 2\pi \color{blue}(1)(\color{green}{43})\]

Answer 11

oooh okay I did it got 277.2

Answer 12

Why did you round up? \[\large SA = 2 \pi (\color{blue}1)^2 + 2\pi \color{blue}(1)(\color{green}{43})\]\[\large \frac{936647}{3388} \approx 276.46015 \]

Answer 13

Something is wrong with your answers, a bit. They are off by a couple decimal places.

Answer 14

yeah I kind of figured

Answer 15

i did 2*3.15= 6.3 because 1 to the 2nd power is still 1
then 2*3.15=6.3*43= 270
so 270+6.3= 277.2

Answer 16

your answer choices have the closest approximation 1 place after the decimal. So in finding our final answer \[\large \frac{936647}{3388} \approx 276.4\color{red}6015\] the 6 would round up our value to be \[\large 276.5 \ in^2\]

Answer 17

o okay i see

Answer 18

Oh, always take the exact value of each variable before finding your answer. That's why you got 277 instead of 276.

you rounded up \(\pi\). \(\pi\) is a very large number that is not restricted to 2 decimal places.

Answer 19

ooh okay

Answer 20

Yep :)

Answer 21

thanks :)

Answer 22

no problem :)