Perimeter and Area Class 7 Practice Set 47 Answers Solutions Chapter 12
Solution & Step-by-Step Answer:
i. Total surface area of cube = 6l² = 6 × (3)² = 6 × 9 = 54 sq. cm.
ii. Total surface area of cube = 6l²
= 6 × 5²
= 6 × 25
= 150 sq. cm.
iii. Total surface area of cube = 6l²
= 6 × (7.2)²
= 6 × 51.84
= 311.04 sq. m.
iv. Total surface area of cube = 6l²
= 6 × (6.8)²
= 6 × 46.24
= 277.44 sq. m.
v. Total surface area of cube = 6l²
= 6 × (5.5)²
= 6 × 30.25
= 181.5 sq. m.
Solution & Step-by-Step Answer:
i. Total surface area of cuboid = 2 (lb + bh + lh) = 2 (12 × 10 + 10 × 5 + 12 × 5) = 2 (120 + 50 + 60) = 2 × 230 = 460 sq. cm.
ii. Total surface area of cuboid
= 2 (lb + bh + lh)
= 2 (5 × 3.5 + 3.5 × 1.4 + 5 × 1.4)
= 2(17.5 + 4.9 + 7)
= 2 × 29.4
= 58.8 sq. cm.
iii. Total surface area of cuboid = 2 (lb + bh + lh)
= 2(2.5 × 2 + 2 × 2.4 + 2.5 × 2.4)
= 2 (5 + 4.8 + 6)
= 2 × 15.8
= 31.6 sq. m.
iv. Total surface area of cuboid = 2 (lb + bh + lh)
= 2 (8 × 5+ 5 × 3.5 + 8 × 3.5)
= 2(40 + 17.5 + 28)
= 2 × 85.5
= 171 sq. m.
Solution & Step-by-Step Answer:
Length of the matchbox (l) = 4 cm, breadth (b) = 2.5 cm, height (h) = 1.5 cm ∴ Total surface area of the matchbox = 2 (lb + bh + lh) = 2 (4 × 2.5 + 2.5 × 1.5 + 4 × 1.5) = 2 (10 + 3.75 + 6) = 2 × 19.75 = 39.5 sq. cm. ∴ 39.5 sq. cm paper will be required.
Solution & Step-by-Step Answer:
Length of the box (l) = 1.5 m, breadth (b) = 1 m, height (h) = 1 m Since, the box is open at top, ∴ Sheet required to make the box = total surface area of the box – area of the top = 2 (lb + bh + lh) – lb = 2lb + 2bh + 2lh – lb = lb + 2bh + 2lh = 1.5 × 1 + 2 × 1 × 1 + 2 × 1.5 × 1 = 1.5 + 2 + 3 = 6.5 sq. m. Since, the inside and outside surface of the box are to be painted. ∴ Area to be painted = 2 × Area of the box = 2 × 6.5 = 13 sq. m. Total cost of painting = area to be painted × rate per sq. m. = 13 × 150 = Rs 1950 ∴ 6.5 sq. m. sheet of metal will be required and the cost of painting the box will be Rs 1950.
Maharashtra Board Class 7 Maths Chapter 12 Perimeter and Area Practice Set 47 Intext Questions and Activities
Solution & Step-by-Step Answer:
(Students should attempt the above activities on their own)
Solution & Step-by-Step Answer:
(Students should attempt the above activities on their own)