Question

A roll of newspaper of length 7000 m and thickness 0.022 cm is rolled into a solid cylinder Find its radius

• A. 7 cm
• B. 140 cm
• C. 35 cm
• D. 70 cm

Answer 1

Answer: (D)

70 cm

The sheet of paper is in the shape of a cuboid Therefore
Volume of the cuboid=Volume of the cylinder
or $7000\times 100\times h\times 0.022=\frac{22}{7}{r}^{2}h$
(Since length is given in meters it is converted into centimeters by multiplication with 100)
or $r^2=\frac{7000\times 100\times 0.022\times 7}{22}=70\times 70$
or r=70 cm