Number of boxes = (Volumes of wooden box in cm3) / (Volume of 1 small box)
= (800 x 700 x 600) / (8 x 7 x 6) = 1000000
As the box is painted from inside, the dimensions of the box from inside are
Length = (21 - 05 - 05) = 20 cm
Breadth = (11 - 05 - 05) = 10 cm and height = (6 - 05) = 5.5
Total number of faced to be painted = 4 walls + One base
The dimensions of two of the walls = 2 x (10 x 5.5)
The dimensions of the remaining two = 2 x (20 x 5.5) and that of the base = (20 x 10 ) and so the total area to be pained = 2 x (10 x 5.5) + 2 x (20 x 5.5) + (20 x 10 ) = 530cm3
Since, the total expenses of painting this area is ?70, the rate of painting
= 70/530 = 0.13 = ? 0.1 per cm3 (approx)
Volume of the sphere = Volume of the water displaced
Let the required height to which the water rises be h.
Then, ?r12h = 4/3 ?r23
? 16 h = 4/3 x 27 ? h = 36/16 = 9/4 cm
Volume of the spherical ball = Volume of the water displaced
? 4/3 ?r3 = ?(12)2 x 6.75
? r3 = 144 x 6.75 x 3/4 = 729
? r = 9 cm
From the formula the net change in volume is given as [x + y + z + (xy + yz + zx)/100 + xyz/(100)2 ] %
Here, x = 200, y = z = -50 (-ve sign for decrease)
= [ 200 + (-50) + (-50) + (200) x (-50) + (-50) x (-50) + (-50) x (200)/100 + (200) x (-50) x (-50)/(100)2 ] %
= 100 + (-10000 + 2500 - 10000)/100 + 500000/100 x 100 ] %
= [ 100 + (-17500)/100 + 50]%
= (150 - 175)% = -25% (-ve sign implies for a decrease )
So, the volume is decreased by 25%.
The net decrease in the surface area of the cube is given by
[x + y + xy/100] %
Here, x = y = 19%
= [-19 + (-19) + (-19) x (-19)/100] %
= [-38 + 361/100] %
= [-38 + 3.61] %= -34.39% (-ve sign implies for decrease)
Let length = 6k, breadth = 5k and height = 4k in cm
? 2(6k x 5k + 5k x 4k + 6k x 4k) = 33300
? 148k2 = 33300
? k2 = 33300/148 = 225
? k = 15
? Length = 90 cm, Breadth = 75 cm, Height = 60 cm
? ?3a = 8?3
? a = 8
? Surface area = 6a2
= (6 x 8 x 8) cm2
= 384 cm2
? l2 + b2 = (10)2 = 100
And l2 + b2 + h2 = (10?300)2 = 200
? h2 = (200 - 100) = 100
? h = 10 m
? ?3 a = 14 x ?3
? a = 14
? Volume of the cube = (14 x 14 x 14)cm3
= 2744 cm3
Length of pencil = ? [(8)2 + (6)2 + (2)2] cm
= ?104 cm
= 2?26
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