Question

13. silver paper covers a packet of 10 chocolate coins of radius 2 cm and thickness 7 mm. How much paper is needed to cover 1000 such packets?​

Answer 1

Answer:

113.142cm2

Step-by-step explanation:

Height =7mm X 10 = 70mm= 7cm

Radius=2cm

Total surface area=2πrh+2πr2

                       =22/7X2X2X7+2X22/7X2X2

                       =113.142cm2

for 1000such packets = 113.142cm2

Answer 2

Answer:

113142.8571 cm^2

Step-by-step explanation:

a packet contains 10 chocolate coins of radius 2 cm and thickness 7 mm

if the chocolate coins are stacked up together, then the dimensions of the packet are

radius= 2cm

height= 7mm X 10 = 70mm = 7cm

since 1 cm = 10 mm

The surface are of this packet can be found as

$SA= 2*\pi *r^2 + 2*\pi *r*h\\SA= 2*\frac{22}{7}*2^2+2*\frac{22}{7}*2*7\\  SA=113.1428571cm^2$

1000 such packets have an area of

113.1428571*1000= 113142.8571 cm^2

Therefore the size of paper needed is 113142.8571 cm^2