Question

A building has 25 cylindrical shaped poles. Each has a radius of 28 cm and a height of 4 cm. Find the cost of the painting curved surface of all poles at the rate of rupees 8 per m2

Answer 1

curved surface area of cylinder is 2πrh.
2×22/7×14×4=352cm².
each pole of painting Rupee's is 352×8=2816.
then the building contain 25 poles
25×352=8800

Answer 2

Hello friends!!

Here is ur answer :

First, the formula used in this question :

Curved surface area of cylinder -

$2 \times \pi \times radius \times height$

Now come to the question,

Radius r of poles = 28 cm

Height h of poles = 4 cm

Curved surface area of 1 pole :

$= 2\pi rh$

$= 2 \times \frac{22}{7} \times 4 \times 28$

$= 2 \times 22 \times 4 \times 4$

$= 704 \: \: {cm}^{2}$

Curved surface area of 25 poles = 25 × 704 cm²

= 17600 cm²

= 1.76 m²

Cost of the painting curved surface of all poles

1 m² = Rs 8

1.76 m² = Rs 8 × 1.76

= Rs 14.08

HOPE IT HELPS YOU..