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प्रश्न
How much iron is needed to make a rod of length 90 cm and diameter 1.4 cm?
उत्तर
Total length = 90 cm
Diameter = 1.4 cm
Radius = 0.7 cm
Total iron required = Volume of cylinder
= πr2h
= `22/7 xx 0.7 xx 0.7 xx 90`
= 138.6 cm3
Thus, 138.6 cm3 of iron is required.
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