Earth dug out = (3 x 2 x 1.5 ) m3 = 9 m3
Area on which earth has been spread = (22 x 14 - 3 x 2 ) m2 = 302 m2
? Rise in level = Volume/Area = (9/302) m = (9 x 100/302) cm = 2.98 cm
Given that,
Volume of sphere = Volume of cone
? (4/3)?r3 = (1/3)?r2h
? 4r = h
Total surface area of the pyramid
= [1/2(perimeter of the base) (Slant height) ] + Area of the base
= 1/2 (4) (4) (8) + 42 = 80 cm2
volume = (2/3)?r3
= (2/3) x ? x 33
= (2/3) x ? x 27
= 18? cm3
Required surface area = 4?r2
= 4 x ? x 42 = 664? sq cm
Given, side of cube, a = 9
? Diagonal of cube = a?3 = 9?3
Let the volume be x3 and 27x3
? Their edges are x and 3x
Now Ratio of their surface area = 6x2 : 54x2 = 1 : 9
Let original length of cube = L
Then, its surface area = 6L2
New edge = (150 x L)/10 = 3L/2
New surface area = 6 x (3L/2)2 = (6 x 9 x L2)/4 = (27/2) x L2
Increase in surface area = (27/2 - 6) x L2 = 15 x L2/2
? Increase percent = (15 x L2/2 ) / (6L2) x 100 % = 125 %
Let the edges of the two cubes be x and y metres
Then, x3 - y3 = 152
and x2 - y2 = 20
Also, x + y = 10
So, x - y = (x2 - y2) / (x + y) = 20/10 = 2
Now, (x3 - y3) / (x - y) = 152/2
? x2 + y2 + xy = 76
? (x + y)2 - xy = 76
? xy = (x + y)2 - 76 = (10)2 - 76 = 24
? l + b + h = 19
and l2 + b2 + h2 = (5?5)2 = 125
? (l + b + h)2 = (19)2
? (l2 + b2+ h2) + 2(lb + bh + lh) = 361
? 2 (lb + bh + lh) = (361 - 125) = 236
? Surface area = 236 cm2
Volume of the Earth taken out = 30 x 20 x 12
= 7200 m3
Area of the remaining portion (leaving the area of dug out portion) = 470 x 30 + 30 x 10
= 14100 + 300 = 14400 m3
Let h be height to which the field is raised by spreading the Earth dug out.
Then, 14400 x h = 7200
? h = 7200/14400 = 0.5 m
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