Solv. Calculus Problems: Max Vol, US Mail Stipulations

[rain]

I have some calculus problems that I don't know if I did it right.

1)A cylindrical box will be tied up with ribbon. The longest piece of ribbon available is 130cm long, and 10cm of that are required for the bow. Find the radius and height of the box with the largest possible volume.
-my answer is h=10cm and r=10cm

2)The U.S. Postal Service stipulates that any boxes sent through the mail must have a length plus girth totaling no more than 108in. Find the dimensions of the box with maximum volume that can be sent through the U.S. mail, assuming that the width and the height of the box are equal.
-my answer is width/height=18in and length=36in

Please check my answer if I got it right, if not, I'll post my steps for you guys to check. Thanks in advance.

 

[MichaelW24]

How do you tie the ribbon?

 

[rain]

hm...like you would tie a birthday cake...a cross on top and bottom, 4 strips on the side...do you get what I mean?

 

[hypermorphism]

Everything looks right.

 

[rain]

thanks a lot. people are nice in here.