Question : A 9 cm solid metallic cube and a solid metallic cuboid having dimensions 5 cm, 13 cm, and 31 cm are melted and recast into a single cube, What is the total surface area (in cm2) of the new cube?
Option 1: 865
Option 2: 1176
Option 3: 1362
Option 4: 2744
Correct Answer: 1176
Solution : Given: Side of cube = 9 cm Cuboid length = 5 cm Breadth = 13 cm Height = 31 cm Volume of cube = $\text{side}^3$ = $9^3$ = 729 cm3 Volume of cuboid = length × breadth × height = 5 × 13 × 31 = 2015 cm3 The volume of recast single cube = Volume of solid metallic cube + Volume of solid metallic cuboid = 729 + 2015 = 2744 cm3 Side of Recast cube: $\text{side}^3$ = 2744 ⇒ side = 14 cm Total surface area of cube = 6 × $\text{side}^2$ = 6 × 14 × 14 = 1176 cm2 Hence, the correct answer is 1176.
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Question : A solid metallic cube of side 9 cm and a solid metallic cuboid having dimensions 5 cm,13 cm, and 31 cm are melted to form a single cube. How much (in INR) is the cost to polish the new cube at a rate of INR 10 per cm2?
Option 1: 8,650
Option 2: 27,440
Option 3: 13,620
Option 4: 11,760
Question : What is the total surface area of a cuboid whose length, breadth, and height are 7 cm, 5 cm, and 9 cm, respectively?
Option 1: 190 cm2
Option 2: 403 cm2
Option 3: 286 cm2,
Option 4: 386 cm2
Question : What is the volume of a cube whose surface area is 54 cm2?
Option 1: 28 cm3
Option 2: 3 cm3
Option 3: 27 cm3
Option 4: 9 cm3
Question : A hemisphere has a 42 cm diameter. Find its curved surface area and the total surface area.
Option 1: 2772 cm2 and 4158 cm2
Option 2: 3772 cm2 and 5158 cm2
Option 3: 4770 cm2 and 4238 cm2
Option 4: 3072 cm2 and 4058 cm2
Question : What is the total surface area of a solid right circular cylinder of radius 7 cm and height 8 cm?$(\pi=\frac{22}{7})$
Option 1: 560 cm2
Option 2: 660 cm2
Option 3: 850 cm2
Option 4: 760 cm2
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