Question

An open metal bucket is in the shape of a frustum of a cone of height
21 cm with radii of its lower and upper ends as 10 cm and 20 cm
respectively. Find the cost of milk which can completely fill the
bucket at 30 per litre.
​

Answer 1

$\huge{\bf{\underline{\overline{\mathfrak{\green{Solution:-}\mid}}}}}$

Given,

Height of the frustum, h=21cm

Radius of upper end, $\bf {r}_{1}$=20cm

Radius of lower end, $\bf {r}_{2}$=10cm

Now,

Volume of frustum of a cone,

$= \tt \frac{1}{3} \pi h( {r}_{1}^{2} + {r}_{2}^{2} + {r}_{1} {r}_{2})$

$=\tt \frac{1}{3} \times 3.14 \times 21 \times( {20}^{2} + {10}^{2} + 20 \times 10)$

$= \tt 3.14 \times 7 \times (400 + 100 + 200)$

$=\tt 21.98 \times 700$

$=\tt 15386 \: {cm}^{3}$

Again, we know that 1000 $\bf {cm}^{3}$ =1 ltr.

So,

$\tt=\frac{15386}{1000}$

$\tt= 15.386$ltr.

Now, cost of milk per liter =Rs.30

So, total cost of milk= Rs.(30×15.386)

= Rs 461.58

Answer 2

Answer:

his answer is right

Step-by-step explanation:

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