Given, r = 7 cm, h = 80 cm
Volume = ?r2h = (22/7) x 7 x 7 x 80
= 12320 cm3
Here, k = 12%
According to the formula,
Percentage increase in volume = [(1 + k/100)3 - 1] x 100%
= [(1 + 12/100)3 - 1] x 100%
= [(1.12)3 - 1] x 100%
= 0.404928 x 100% = 40.4928%
Here, x = y = -19%
According to the formula,
Percentage decrease in surface area
= [x + y + xy/100]%
= [- 19 - 19 + (-19) x (-19) /100]%
=[-38 + 361/100]%
= [-38 + 3.61]% = -34.39 %
Let the edge of a square be x. and sum of its edges = 12 x
Now, by condition, x3 = 12x
? x(x2 - 12) = 0
? Its total surface area = 6x2 = 6(12) = 72 sq units
Volume of the cuboid = 720 cm3
Height of the cuboid = Volume of the cuboid / Base area of the cuboid
= 720 / 72 = 10 cm [By Hit Trail]
Surface area of the cuboid = 2 (lb + bh + hl)
= 2(9 x 8 + 8 x 10 + 10 x 9 )
= 2 (72 + 80 + 90)
= 2 x 242
= 484 cm2
? It is obvious that length, breadth and height of the cuboid is 9 cm, 8 cm and 10 cm.
Surface area of 1 brick
= 2 (lb + bh + lh)
= 2(22.5 x 10 + 10 x 7.5 + 7.5 x 22.5)
= 2(225 + 75 + 168.75)
= 2 x 468.75 = 937.50 cm2
= 93750/(100 x 100) = 0.09375 sq m
? Number of bricks = Total area/Surface area of 1 brick
= 9.375 / 0.09375 = 100
Total surface area of cylinder = 2?r(h + r)
Given that, r = 14/2 = 7 cm, h = 40 cm
? Required total surface area = 2 x (22/7) x 7 x (40 + 7)
= 44 x 47 = 2068 sq cm
Given, lateral surface area = 94.2 sq cm
? 2?rh = 94.2
? r = 94.2/(2?h) = 94.2/(2 x 3.14 x 5) = 3 cm
Given, r1 = 1 cm, h1 = 30 cm, h2 = 300 cm.
Volume of rod = Volume of wire
? ?r12h1 = ?r22h2
? ? x (1)2 x 30 = ? x r22 x 300
? r22 = 30/300
? r2 = 1/?10 cm
? diameter = 2r2
= 2 x 1/?10 = 2/?10cm.
Let the height and radius and radius of solid cylinder be h and r cm respectively
Given that, radius (r) = 5 cm
and total surface area = 660 cm2
? 2?rh + 2?r2 = 660
? 2?r(h + r) = 660
? (h + 5) = 330/5? = 330/5 x 7/22
? h = 66 x (7/22) - 5 = 21 - 5
? Required height = 16 cm
Curved surface area of the cylinder = 2?rh
= 2 x (22/7) x 7 x 160
= 7040 sq cm
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