Posted by Taylor on .
I already posted this, but wanted to say that I have the answers and it is 1.68 is less than or equal to x is less than or equal to 9.10
Cone Problem Beginning with a circular piece of paper with a 4 inch radius, as shown in (a), cut out a sector with an arc of length x. Join the two radial edges of the remaining portion of the paper to form a cone with radius r and height h, as shown in (b). What length of arc will produce a cone with a volume greater than 21 in.^3?

Math 
Reiny,
Emma asked the same question on Saturday.
http://www.jiskha.com/display.cgi?id=1293931313