6cm diameter discs are cut from a sheet 130cm long and 70cm wide.(a)How many discs can be cut in this way (b) what area of the sheet is wasted?
(My working so far).
Area of rectangle=L*B
130*70=9100cm^2
area of circle=22/7 *(6/2)^2=28.286cm^2
(a)no of discs cut=9100/28.286=321
pls help with the (b) part of the question.which is: what area of the sheet is wasted?
just subtract what was used from the original amount:
9100 - 321*28.286
However, that assumes that all the leftover parts could be combined to form new circles; not very likely. A better way to look at it is to decide how many rows and columns of discs could be cut.
130/6 = 21.67
70/6 = 11.67
So, you have 21 rows of 11 discs, or 231 discs
Now the wastage is 9100 - 231*28.286
In fact, however, there are better ways of packing the discs onto the sheet than a square lattice, but that gets quite complicated.