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Outer part surface area = 2πRh Inner part surface area = 2πrh Area of shaded portion = 2πR² - (πr)² = π(R² - r²) Total surface area = 2πRh + 2πrh + 2π(R² - r²) = 2π(R+r) [h + R - r] = 2π(R+r) [h + thickness] Required surface area = 2π(R+r) [h + thickness] = 2 × 22/7 × (12.5 + 11.5) × 21 = 132 × 24 = 3168
If D and E are the mid points of AB and AC respectively of ∆ ABC, then the ratio of the areas of ADE and BCED is ?
A bag contains notes of Rs.10, Rs.20, and Rs.50 in the ratio of 1:3:5. If the total value of money in the bag is Rs.1920, find the number of Rs.20 notes.
The simplest form of the ratio of 2.5 : 6.5 is _____.