• question_answer The diameters of the lower and upper ends of a bucket in the form of a frustum of a cone are 10 cm and 30 cm respectively. If its height is 24 cm, find: (i) The area of the metal sheet used to make the bucket. (ii) Why we should avoid the bucket made by ordinary plastic? [Use $\pi =3.14$]

 Given, Height of frustum, h = 24 cm. Diameter of lower end = 10 cm. $\therefore$      Radius of lower end, r = 5 cm. Diameter of upper end = 30 cm. $\therefore$      Radius of upper end, R = 15 cm. Slant height,       $l=\sqrt{{{h}^{2}}+{{(R-r)}^{2}}}$ $=\sqrt{{{(24)}^{2}}+{{(15-5)}^{2}}}$ $=\sqrt{576+100}$ $=\sqrt{676}$ $=26\,cm$ (i) Area of metal sheet used to make the bucket = CSA of frustum + Area of base $=\pi l(R+r)+\pi {{r}^{2}}$ $=\pi [26(15+5)+{{(5)}^{2}}]$ $=3.14(26\times 20+25)$ $=3.14(520+25)$ $=3.14\times 545$ $=1711.3\,\,c{{m}^{2}}$ (ii) We should avoid the bucket made by ordinary plastic because plastic is harmful to the environment and to protect the environment its use should be avoided.