Question

The inner diameter of a wells 2.5 metres and it is 8 metres deep .What would be the cost of cementing its inside at 350 rupees per square metre?​

Answer 1

Answer:

hum kaha kisi ko pata ha bhaya Shri ediot

Answer 2

..Question..

The inner diameter of a well is 2.5 metres and it is 8 metres deep .What would be the cost of cementing its inside at 350 rupees per square metre?

..Answer..

Given ,

ㅤㅤㅤ> Diameter of the well = 2.5 m

ㅤㅤㅤ•°• radius of the well ㅤ= 2.5/2

ㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤ= 1.25 m

ㅤㅤㅤ> Height of the well = 8 m

ㅤㅤㅤ> cost of cementing per m² = rs 350

>> We know that ,

ㅤㅤㅤ> C.S.A. of cylinder is = 2πrh

•°• putting the values here , we get ,

= 2 π r h

= 2 × 22/7 × 1.25 × 8

= 44/7 × 10

= 440 / 7

= 62.85

Curved Surface Area of the well = 62.85 m²

°•° a well have only 1 open side , rest all are closed / cemented

•°• area of the bottom

= πr²

= 22/7 × ( 1.25 )²

= 22/7 × 1.56

= 34.32 / 7

= 4.9

•°• area of the bottom = 4.9 m²

>> combining all the areas

ㅤㅤㅤㅤ= 62.85 + 4.9

ㅤㅤㅤㅤ= 67.75 m²

°•° cost of 1 m² cementing = rs 350

•°• cost of cement. 67.75 m² = 67.75 × 350

ㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤ= rs 23712

____________________

Another way of doing the equation >

Given ,

ㅤㅤㅤ > Diameter of the well = 2.5 m

ㅤㅤㅤ •°• radius of the well = 1.25 m

ㅤㅤㅤ > Height of the well = 8 m

ㅤㅤㅤ > cost of cementing per m² = 350

>> We know that ,

ㅤTotal surface area of cylinder = 2πr(r+h)

•°• putting the values here ,

= 2 π r ( r + h )

= 2 × 22/7 × 1.25 ( 1.25 + 8 )

= 44/7 × 1.25 × 9.25

= 44/7 × 11.56

= 72.67

•°• Total Surface Area of the well = 72.67 m²

> area of the mouth of the well ,

= π r²

= 22/7 × ( 1.25 )²

= 22/7 × 1.56

= 4.9

area of the mouth = 4.9 m²

decreasing the area of mouth from the total surface area of the well , we get

= 72.67 - 4.9

= 67.75 ( approx )

> cost of cementing per m² = rs 350

•°• " " " 67.75 m² = 67.75 × 350

ㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤ= rs 23712

Hence both are same ✓✓

ㅤㅤ ㅤ ꧁ ʙʀᴀɪɴʟʏ×ᴋɪᴋɪ ꧂

ㅤ