Robert made a tunnel using some identical cubes (fig.1). When he got bored, he rearranged the tunnel into a complete pyramid (fig.2). How many cubes from the original tunnel did he not use for the pyramid?
A. 34 B. 29 C. 22 D. 18 E. 15
Subscribe to:
Post Comments (Atom)
its 18
ReplyDeleteThe center layer is 18 blocks. But the question is how many blocks were NOT used from the original design...
ReplyDeleteim just doing this fast and mentally
ReplyDelete72 - 41? ... =31 ?
# of blocks used for tunnel : 20+12+12+20 = 64
ReplyDelete# of blocks used for pyramid ; 25+9+9+3 = 46
Diff = 18 (D)