Question

The height of a right circular cylinder is 10.5 m. Three times the sum of the areas of its two circular faces is twice the area of the curved surface. Fnd the volume of the cylinder. [Hint : 3(πr²) = 2πr(10.5) => r = 7]

Answer 1

volume of cylinder- πr2h
22/7×7×7×10.5
22×7×10.5
154×10.5
1617 is ans

Answer 2

Answer:

The total cost required to cover 20 wooden boxes is Rs. 315.

The dimensions of the wooden box is 25 cm × 25 cm × 40 cm.

The total surface area of the box is given by

TSA = 2(lb + bh + hl)

TSA = 2(25×25 + 25×40 + 25×40) = 5250 sq. cm

TSA = 5250 / 10000 = 0.525 sq. m

Now the rate of 1 sq. m of cloth is Rs. 30.

Cost of covering 1 box = Rs. 30 × 0.525 = Rs. 15.75 .

Now, Cost of covering 20 such boxes = Rs. 15.75 × 20 = Rs. 315.

Total cost of covering 20 boxes is Rs. 315.