Question

4. John wants to cover a box entirely with silver paper. How many square centimetres

of silver paper will he need if the box measures 22 cm long, 16 cm wide, and 10 cm deep?
A. 1 464 sq cm
B. 3 520 sq cm
C.4 164 sq cm
D. 5 230 sq cm

5. How many square decimetres of cardboard is needed to make a cubical soda cracker box measuring 2.5 dm on each edge?
A. 5.0 sq dm
B. 6.25 sq dm
C. 37.5 sq dm
D. 7.35 sq dm

6. Suppose you want to produce ping pong balls with 1.5 dm radius. What is the least
amount of rubber you would need if you want to produce 10 ping pong balls?
A. 262.8 sq dm
B. 272.6 sq dm
C. 282.6 sq dm
D. 286.2 sq dm​

Answer 1

4.

l=22cm

b:16cm

h:10cm

surface area =2(lb+bh+lh)=2(22*16+16*10+22*10)

=1464cm²

5.

a=2.5dm

area cubical soda cracker box=6a²=6*2.5²=37.5dm²

6.

r=1.5dm

area of ball=4πr²=4π×1.5²=28.27dm² per ball

for 10 bal =28.27×10=282.6dm²