题目

While astronauts in space get to do many exciting things, they miss out on ordinary things that we all take for granted─being able to walk on firm ground, hanging out with family and digging into a slice of hot steaming pizza. Though not much can be done about the first two things, there may soon be a solution to the third one, thanks to this cool 3-D pizza printer! About a year ago, NASA offered $125,000 to Anjan Contractor, a 3-D technology expert, to build a device（设备）that would allow astronauts to make pizza on demand. The mechanical engineer promised that his invention 6．一位同学在使用天平与量筒测量小石块密度实验中，采用了蜡块代替了小石块（蜡块浮在水面上），然后按照测小石块密度的步骤得出了蜡块的密度，请问这个密度与蜡块的实际密度比较是否准确，如果不准确，可以在实验中采取些什么办法使测量的结果准确？