Question 1092750: Plz help me to do this sum :- The diameter of base of a chimney is 80 CM and hieght is 12.5 m. What will be the cost of painting this chimney from outside at the rate of Rs 140 per square metre? π=3.14
(Plz reply me fast. It's argent.)
Found 3 solutions by Theo, Boreal, MathTherapy:
Answer by Theo(13342)   (Show Source):
You can put this solution on YOUR website! the diameter is 80 centimeters
the height is 12.5 meters.
the chimney forms a right cylinder.
the formula for the lateral surface area of a right cylinder is equal to 2 * pi * r * h
pi = 3.14.
r = half of the diameter = 40 centimeters.
h = the height which is equal to 12.5 meters.
one centimeter is equal to .01 meters.
convert everything to meters to get:
pi = 3.14.
r = half of the diameter = .4 meters.
h = the height which is equal to 12.5 meters
the formula of 2 * pi * r * h for the lateral surface area of the chimney becomes 2 * 3.14 * .4 meters * 12.5 meters.
this results in a lateral surface area of 31.4 square meters.
at rs 140 per square meter, the cost will be 140 * 31.4 = rs 4396.
Answer by Boreal(15235)  (Show Source):
You can put this solution on YOUR website! Assuming this is a cylinder shaped object.
Diameter is 80 cm, so circumference is 80*3.14 cm =251.2 cm or 2.512 m.
The height is 12.5 m
The area is circumference * height or 31.4 sq m.
31.4 m^2*140 R/m^2=439.6 R.
Answer by MathTherapy(10552)  (Show Source):
You can put this solution on YOUR website!
Plz help me to do this sum :- The diameter of base of a chimney is 80 CM and hieght is 12.5 m. What will be the cost of painting this chimney from outside at the rate of Rs 140 per square metre? π=3.14
(Plz reply me fast. It's argent.)
You're being asked to find the surface area of the chimney and then the cost to paint this surface area.
As is obvious, the chimney is in the shape of a cylinder, but only the OUTSIDE of the cylinder is needed. This formula is:  , with D being the diameter, and h, the height of the cylindrical chimney.
Now, the diameter is in cm (80 cm = .8 m), but the height is in meters, and the cost is also in meters. Therefore, it's best to keep all units in METERS.
We then get OUTSIDE SURFACE AREA as:  , and with the cost being Rs 140 per sq meter, we get: 
IGNORE anyone who says otherwise!!
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