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Find the area (in square metres) of a rectangle whose
(i) length = 6.2 m, breadth = 2.3 m
(ii) length = 210 cm, breadth = 145 cm -
Find the area (in square centimetres) of a square whose side is
(i) 3.1 cm
(ii) 1.5 dm -
Find the area (in square metres) of a square whose side is 12.4 dam.
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Find the area of a rectangular field in acres whose sides are:
(i) 250 m and 160 m
(ii) 80 m 3 dm and 140 m -
A wall measures 9.5 m by 8.5 m. There is a door on it measuring 2.2 m by 1.8 m. If painting costs Rs 3.25 per m², find the cost of painting the wall (excluding the door).
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A wire is bent into a rectangle of size 44 cm by 28 cm. The same wire is then re-bent to form a square.
(a) Find the side of that square.
(b) Which shape (the original rectangle or the square) encloses more area? Give the areas. -
How many square metres of glass are needed for a window that has 15 panes, each measuring 30 cm by 18 cm?
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A tile measures 12 cm by 15 cm. How many such tiles are required to cover a wall of size 2.8 m by 3.6 m? Also find the total cost if each tile costs Rs 3.
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A room measures 8.4 m by 5.6 m. It is to be paved with rectangular tiles each 25 cm by 12 cm. Find total number of tiles required and the total cost if each tile costs Rs 2.75.
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One side of a square field is 185 m. Find the cost of turfing the field at the rate of Rs 1.80 per m².
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A rectangular field is 320 m by 210 m. How long will it take a girl to go twice around the field if she walks at 1.75 m/s?
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A corridor is 9 m long and 7 m wide. Canvas sheets measuring 2 m by 1 m are used to cover it. If each sheet costs Rs 9, find the cost to cover the corridor (use whole sheets only).
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A playground is 70 m 45 cm by 30 m 25 cm.
(i) Find the cost of turfing it at Rs 3 per m².
(ii) How long will a man take to walk three times around it at 2 m/s? -
A lane 200 m long and 6 m wide is to be paved with bricks each 20 cm by 10 cm. Bricks cost Rs 820 per thousand. Find the number of bricks required and the total cost.
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From a sheet of paper 132 cm by 92 cm, how many envelopes of size 16 cm by 8 cm can be cut (assume all envelopes are cut without waste by arranging them in rows and columns)?
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The width of a cloth roll is 150 cm. How many metres of cloth are required to make 25 diapers if each diaper needs a piece 45 cm by 30 cm? (Assume the 30 cm side is taken across the width of the cloth.)
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A room 6.2 m by 5.4 m is carpeted at a total cost of Rs 3840. The carpet roll is 80 cm wide. Find the cost of the carpet per metre (i.e., cost per running metre of the roll).
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A room is 8.5 m long, 7.2 m broad and 3.6 m high. It has one door 2.2 m × 1.5 m and two windows of sizes 1.2 m × 1.5 m and 1.5 m × 1.2 m. Find the cost of whitewashing the walls at Rs 4.50 per m² (exclude floor and ceiling; exclude door and windows area).
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A hall is 40 m long and 28 m broad. Allow 96 m² for doors and windows. If papering the walls costs Rs 9 per m² and the total papering cost is Rs 9,408, find the height of the hall.
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A rectangular swimming pool is 25 m long and 12 m wide. It is surrounded by a 1.5 m wide path. Find the area of the path and the cost of cementing it at the rate of Rs 85 per m².
ANSWER KEY
1. (i) Area = 6.2 × 2.3 = 14.26 m².
(ii) Convert to metres: 210 cm = 2.10 m, 145 cm = 1.45 m. Area = 2.10 × 1.45 = 3.045 m².
2. (i) Side = 3.1 cm ⇒ Area = (3.1)² = 9.61 cm².
(ii) 1.5 dm = 15 cm ⇒ Area = 15 × 15 = 225 cm².
3. 1 dam = 10 m. Side = 12.4 dam = 124 m. Area = 124² = 15,376 m².
4. (i) Area = 250 × 160 = 40,000 m². 1 acre ≈ 4,046.8564224 m².
Area in acres = 40,000 ÷ 4,046.8564224 ≈ 9.884 acres (approx).
(ii) 80 m 3 dm = 80.3 m. Area = 80.3 × 140 = 11,242 m².
In acres = 11,242 ÷ 4,046.8564224 ≈ 2.778 acres (approx).
5. Wall area = 9.5 × 8.5 = 80.75 m². Door area = 2.2 × 1.8 = 3.96 m².
Net area = 80.75 − 3.96 = 76.79 m². Cost = 76.79 × 3.25 = Rs 249.57 (≈ Rs 249.57).
6. Rectangle perimeter = 2(44 + 28) = 2 × 72 = 144 cm. Re-bent as square ⇒ side = 144 ÷ 4 = 36 cm.
Area of rectangle = 44 × 28 = 1,232 cm². Area of square = 36² = 1,296 cm².
Square encloses more area (1,296 cm² > 1,232 cm²).
7. Each pane area = 30 cm × 18 cm = 540 cm² = 0.054 m². For 15 panes: total = 15 × 0.054 = 0.81 m².
8. Tile = 12 cm × 15 cm = 0.12 × 0.15 = 0.018 m². Wall area = 2.8 × 3.6 = 10.08 m².
Number of tiles = 10.08 ÷ 0.018 = 560 tiles exactly. Cost = 560 × 3 = Rs 1,680.
9. Room area = 8.4 × 5.6 = 47.04 m². Tile area = 0.25 × 0.12 = 0.03 m².
Number of tiles = 47.04 ÷ 0.03 = 1,568 → whole tiles ⇒ 1,568 tiles.
Cost = 1,568 × 2.75 = Rs 4,312.00.
10. Area = 185² = 34,225 m². Cost = 34,225 × 1.80 = Rs 61,605.00.
11. Perimeter = 2(320 + 210) = 2 × 530 = 1,060 m. Twice around = 2 × 1,060 = 2,120 m.
Time = distance ÷ speed = 2,120 ÷ 1.75 ≈ 1,211.43 s (≈ 20 min 11.43 s).
12. Corridor area = 9 × 7 = 63 m². Each sheet = 2 × 1 = 2 m². Sheets needed = 63 ÷ 2 = 31.5 ⇒ whole sheets ⇒ 32 sheets.
Cost = 32 × 9 = Rs 288.
13. Length = 70 + 0.45 = 70.45 m. Breadth = 30 + 0.25 = 30.25 m. Area = 70.45 × 30.25 = 2,131.1125 m².
Cost at Rs 3/m² = 2,131.1125 × 3 = Rs 6,393.34 (approx).
Perimeter = 2(70.45 + 30.25) = 2 × 100.7 = 201.4 m. Three rounds = 3 × 201.4 = 604.2 m. Time at 2 m/s = 604.2 ÷ 2 = 302.1 s (≈ 5 min 2.1 s).
14. Lane area = 200 × 6 = 1,200 m². Brick area = 0.20 × 0.10 = 0.02 m². Bricks needed = 1,200 ÷ 0.02 = 60,000 bricks.
Cost = (60,000 ÷ 1,000) × 820 = 60 × 820 = Rs 49,200.
15. Fit envelopes in rows and columns: along length 132 cm ÷ 16 cm = 8 (whole), along breadth 92 ÷ 8 = 11 (whole). Total = 8 × 11 = 88 envelopes.
16. Cloth width = 150 cm. Each diaper piece = 45 cm × 30 cm; assume 30 cm is across width. Number across width = floor(150 ÷ 30) = 5 diapers per length-row. For 25 diapers you need ceil(25 ÷ 5) = 5 rows. Each row uses 45 cm (0.45 m) of length. Total length = 5 × 0.45 = 2.25 m.
17. Room area = 6.2 × 5.4 = 33.48 m². Roll width = 0.8 m. Length of roll used = 33.48 ÷ 0.8 = 41.85 m. Cost per metre = 3,840 ÷ 41.85 ≈ Rs 91.76 per m.
18. Perimeter = 2(8.5 + 7.2) = 2 × 15.7 = 31.4 m. Wall area = perimeter × height = 31.4 × 3.6 = 113.04 m².
Openings area = door 2.2×1.5 = 3.30 m²; windows = 1.2×1.5 = 1.80 m² and 1.5×1.2 = 1.80 m² ⇒ total openings = 3.30 + 1.80 + 1.80 = 6.90 m².
Net area = 113.04 − 6.90 = 106.14 m². Cost = 106.14 × 4.50 = Rs 477.63 (approx).
19. Let height = h. Perimeter = 2(40 + 28) = 136 m. Area to paper = (perimeter × h) − 96. Cost = 9 × [(136h) − 96] = 9,408.
So (136h − 96) = 9,408 ÷ 9 = 1,045.333… ⇒ 136h = 1,045.333… + 96 = 1,141.333… ⇒ h = 1,141.333… ÷ 136 ≈ 8.392 m.
20. Area of path = 120 m², Cost = Rs 10,200