Question
A rectangular piece of copper foil of length 42 cm and
area 924 cm2 is folded along its width to form a cylinder such that there is only one layer of copper foil on any part of the cylinder. What is the volume (in cm3) of the cylinder so formed?Solution
Width of the rectangular piece of copper foil = 924/42 = 22 cm Since the foil is folded along its width to form a cylinder without any double layer, circumference of the cylinder formed = width of the rectangular foil Also, height of the cylinder so formed = length of the rectangular copper foil So, 2 × π × radius = 22 Radius of cylinder = 22 ÷ (2 × 22/7) = (22/44) × 7 = 3.5 cm So, volume of the cylinder so formed = π × (radius)2 × height = (22/7) × 3.5 × 3.5 × 42 = 1617 cm³
2Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 4Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 5Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 19Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 70...
6000 3002 1503 ? 378.75 191.375 97.6875
...If  204    196       223   x  284
Then, what is the average of the numbers of the above series?
...8   24    12    ?   18     54
3 ? 7 16 71 346
...104   106   110   113   ?   126
12, 18, 28, 42, 52, ?
18Â Â Â Â Â Â Â Â Â Â Â Â 29 Â Â Â Â Â Â Â Â Â Â Â Â Â Â 51 Â Â Â Â Â Â Â Â 84 Â Â Â Â Â Â Â Â 128 Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â 182
5, 8, 17, ?, 37, 48
(32.03 + 111.98) ÷ 18.211 = 89.9 – 20.23% of ?
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