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सी.आई.एस.सी.ई.आईसीएसई ICSE Class 8

A Cube of Edge 6 Cm and a Cuboid with Dimensions 4 Cm X X Cm X 15 Cm Are Equal in Volume. Find: (I) the Value of X. (Ii) the Total Surface Area of the Cuboid. (Iii) the Total Surface Area of the Cube.

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प्रश्न

A cube of edge 6 cm and a cuboid with dimensions 4 cm x x cm x 15 cm are equal in volume. Find:
(i) the value of x.
(ii) the total surface area of the cuboid.
(iii) the total surface area of the cube.
(iv) which of these two has a greater surface and by how much?

योग
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उत्तर

Edge of a cube = 6 cm
Volume = a3 = (6)3 = 216 cm3
Dimensions of a cuboid = 4 cm x x cm x 15 cm
Volume = 60x cm3
The volume of both is equal

(i) ∴ `60x = 216 ⇒ x = 216/60 = 36/10`

∴ x = 3.6 cm

(ii) Total surface area of cuboid

= 2[lb + bh + hl]

= `2[4 xx 3.6 + 3.6 xx 15 + 15 xx 4]` cm2

= 2[14.4 + 54.0 + 60] cm2

= `128.4 xx 2 = 256.8` cm2

(iii) Total surface area of cube

= `6a^2 = 6(6)^2 = 6 xx 36 = 216` cm2

(iv) Difference of surface areas = 256.8 - 216

= 40.8 cm2

∴ Surface area of cuboid is greater

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अध्याय 23: Surface Area, Volume and Capacity - Exercise 21 (C) [पृष्ठ २४१]

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सेलिना Concise Mathematics [English] Class 8 ICSE
अध्याय 23 Surface Area, Volume and Capacity
Exercise 21 (C) | Q 4 | पृष्ठ २४१

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