A bucket made of a aluminium sheet is of height 20 cm

Solution:

The height of the bucket is 20cm. The radii of the upper and lower circles of the bucket are r1 =25cm and r2 =10cm respectively.

The slant height of the bucket is

$l=\sqrt{\left(r_{1}-r_{2}\right)^{2}+h^{2}}$

$=\sqrt{(25-10)^{2}+20^{2}}$

$=\sqrt{625}$

 

$=25 \mathrm{~cm}$

The surface area of the used aluminium sheet to make the bucket is

$S_{1}=\pi\left(r_{1}+r_{2}\right) \times l+\pi r_{2}^{2}$

$=\pi \times(25+10) \times 25+\pi \times 10^{2}$

$=\pi \times 35 \times 25+100 \pi$

 

$=3061.5 \mathrm{~cm}^{2}$

Therefore, the total cost of making the bucket is

$=\frac{3061.5}{100} \times 70$

$=2143.05$

Hence the total cost is Rs.2143.05