Question

1) How many bricks each 25 cm long, 10 cm wide and 7.5 cm thick will be required for a wall 20 m long. 2 m high and 0.75 m thick? If bricks sell at Rs 900 per thousand, what will it cost to build the wall?

2) How many cubic metres of earth must be dug out to sink a well which is 16 m deep and which has a radius of 3.5 m? If the earth taken out is spread over a rectangular plot of dimensions 25 mx16 m. what is the height of the platform so formed?​

Answer 1

Step-by-step explanation:

hi friend!!

here you go refer the attachment

Answer 2

✬ Question 1 ✬

✴ Given :

• Dimensions of brick are length 25 cm, Breadth 10 cm and width 7.5 cm. Dimensions of wall is 20 m, 2 m, 0.75 m.

▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬

✴ To Find :

• What is the total no. of bricks required and what is its cost.

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✴ Solution :

Formula Used :

$\large{\orange{\bigstar}}\: \: \:{\underline{\boxed{\red{\sf{ Volume{\small_{(Cuboid) }}= Length \times Width \times Height}}}}}$

$\qquad{━━━━━━━━━━━━━━━━━━━━━━━━━━}$

Volume of brick :

${\implies{\qquad{\sf{ Volume{\small_{(Brick) }}= L \times W \times H}}}}$

${\implies{\qquad{\sf{ Volume{\small_{(Brick) }}= 25 \times 10 \times 7.5}}}}$

${\implies{\qquad{\sf{ Volume{\small_{(Brick) }}= 250 \times 7.5}}}}$

$\qquad{\large{\blue{\longrightarrow{\underline{\pink{\sf{ 1875 \: cm³}}}}}}}$

$\qquad{━━━━━━━━━━━━━━━━━━━━━━━━━━}$

Volume of Wall :

${\implies{\qquad{\sf{ Volume{\small_{(Wall) }}= L \times W \times H}}}}$

${\implies{\qquad{\sf{ Volume{\small_{(Wall) }}= 2000 \times 200 \times 75}}}}$

${\implies{\qquad{\sf{ Volume{\small_{(Wall) }}= 400000 \times 75}}}}$

$\qquad{\large{\blue{\longrightarrow{\underline{\pink{\sf{ 30000000\: cm³}}}}}}}$

$\qquad{━━━━━━━━━━━━━━━━━━━━━━━━━━}$

No. of bricks required :

${\implies{\qquad{\sf{ No. {\small_{(Bricks) }}= \dfrac{ Vol. \:of \:wall }{Vol. \: of\: bricks }}}}}$

${\implies{\qquad{\sf{ No. {\small_{(Bricks) }}= \dfrac{ 30000000 }{1875}}}}}$

${\implies{\qquad{\sf{ No. {\small_{(Bricks) }}= \cancel\dfrac{ 30000000 }{1875}}}}}$

$\qquad{\large{\blue{\longrightarrow{\underline{\pink{\sf{ 16000 \: bricks}}}}}}}$

$\qquad{━━━━━━━━━━━━━━━━━━━━━━━━━━}$

Cost of Bricks :

${:\longmapsto{\qquad{\sf{ Cost{\small_{(Bricks) }}= \dfrac{No. \:of \:bricks }{1000} \times 900}}}}$

${:\longmapsto{\qquad{\sf{ Cost{\small_{(Bricks) }}= \dfrac{16\cancel{000} }{\cancel{1000}} \times 900}}}}$

${:\longmapsto{\qquad{\sf{ Cost{\small_{(Bricks) }}= 16 \times 900}}}}$

$\qquad\large{\red{:\longmapsto{\underline{\boxed{\green{\sf{ ₹ \:14400 }}}}}}}{\pink{\bigstar}}$

${\green{\underline{▬▬▬▬▬}}{\pink{\underline{▬▬▬▬▬}}{\orange{\underline{▬▬▬▬▬}}{\purple{\underline{▬▬▬▬▬▬}}}}}}$

✬ Question 2 ✬

✴ Given :

• Dimensions of well are depth is 16 m and radius is 3.5 m.
• Dimensions of the rectangular plot are 25 m * 16 m.

▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬

✴ To Find :

• What is the height of platform formed ?

▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬

✴ Solution :

Formula Used :

$\large{\orange{\bigstar}}\: \: \:{\underline{\boxed{\red{\sf{ Volume{\small_{(Cylinder) }}= πr²h}}}}}$

Volume of earth taken from well :

${\implies{\qquad{\sf{ Volume{\small_{(Earth \:taken \:out) }}= πr²h}}}}$

${\implies{\qquad{\sf{ Volume{\small_{(Earth \:taken \:out) }}= \dfrac{22}{7} \times (3.5)² \times 16 }}}}$

${\implies{\qquad{\sf{ Volume{\small_{(Earth \:taken \:out) }}= \dfrac{22}{7} \times 12.25 \times 16 }}}}$

${\implies{\qquad{\sf{ Volume{\small_{(Earth \:taken \:out) }}= \dfrac{22}{7} \times 196 }}}}$

${\implies{\qquad{\sf{ Volume{\small_{(Earth \:taken \:out) }}= \dfrac{22}{\cancel7} \times \cancel{196} }}}}$

${\implies{\qquad{\sf{ Volume{\small_{(Earth \:taken \:out) }}= {22} \times 28 }}}}$

$\qquad{\large{\blue{\longrightarrow{\underline{\pink{\sf{ 616\: m³}}}}}}}$

$\qquad{━━━━━━━━━━━━━━━━━━━━━━━━━━}$

Height of platform :

${:\longmapsto{\sf{ Volume{\small_{(Platform) }}= Volume{\small_{(Well) }}}}}$

${:\longmapsto{\qquad{\sf{ L \times B \times H = 616 \: m³ }}}}$

${:\longmapsto{\qquad{\sf{ L \times B \times H = 616 \: m³ }}}}$

${:\longmapsto{\qquad{\sf{ 25 \times 16 \times H = 616 \: m³ }}}}$

${:\longmapsto{\qquad{\sf{ 352 \times H = 616 \: m³ }}}}$

${:\longmapsto{\qquad{\sf{ H = \dfrac{616}{352}}}}}$

${:\longmapsto{\qquad{\sf{ H = \cancel\dfrac{616}{352}}}}}$

$\qquad{\large{\red{:\longmapsto{\underline{\boxed{\green{\sf{ 1.75 \: m }}}}}}}}{\pink{\bigstar}}$

$\qquad{━━━━━━━━━━━━━━━━━━━━━━━━━━}$

Therefore :

❝ Height of the rectangular platform is 1.75 m. ❞

${\green{\underline{▬▬▬▬▬}}{\pink{\underline{▬▬▬▬▬}}{\orange{\underline{▬▬▬▬▬}}{\purple{\underline{▬▬▬▬▬▬}}}}}}$