28. A manufacturer involves twelve children in colouring pen stands al

1.	28. A manufacturer involves twelve children in colouring pen stands all over excludingbase which are in the shape of a cylinder made of wood of thickness 2 cm. Theinner radius of the cylinder is 4 cm and its height is 14 cm. Find the area they hadto paint if 50 pen stands were given to them for painting.
Answer» Find the area painted as follows: Find the outer surface area of the cylindrical pencil stand.Area of the outer cylinder surface is: Perimeter of the cylinder× height of the cylinder πD × H = 22/7 × 12× 14 = 528 cm² Area of the inner cylindrical part: (assuming that the base is 2cm thick as well)The inner height would be 12 cm πD × H= 22/7 × 8× 12 = 301.632cm² The area of the top part painted:Area of the larger circular surface - smaller surface πR² -πr² = 3.142×6² - 3.142× 4² = 113.112 - 50.272 = 62.84cm² Add the area to find the total area painted: 528 cm² + 62.84cm² +301.632cm² = 892.472cm² The area painted in 1 stand is 892.472 cm² The area of 50 such stands is 892.472 cm²× 50 = 44623.60 cm² hit like if you find it useful answer is wrong correct answer is 347600/7 cm^2

28. A manufacturer involves twelve children in colouring pen stands all over excludingbase which are in the shape of a cylinder made of wood of thickness 2 cm. Theinner radius of the cylinder is 4 cm and its height is 14 cm. Find the area they hadto paint if 50 pen stands were given to them for painting.

Answer»

Find the area painted as follows:

Find the outer surface area of the cylindrical pencil stand.Area of the outer cylinder surface is:

Perimeter of the cylinder× height of the cylinder

πD × H = 22/7 × 12× 14 = 528 cm²

Area of the inner cylindrical part: (assuming that the base is 2cm thick as well)The inner height would be 12 cm

πD × H= 22/7 × 8× 12 = 301.632cm²

The area of the top part painted:Area of the larger circular surface - smaller surface

πR² -πr² = 3.142×6² - 3.142× 4² = 113.112 - 50.272 = 62.84cm²

Add the area to find the total area painted:

528 cm² + 62.84cm² +301.632cm² = 892.472cm²

The area painted in 1 stand is 892.472 cm²

The area of 50 such stands is 892.472 cm²× 50 = 44623.60 cm²

hit like if you find it useful

answer is wrong

correct answer is 347600/7 cm^2