Question
The height of a solid cylinder is 30 cm and the diameter
of its base is 10 cm. Two identical conical holes each of radius 5 cm and height 12 cm are drilled out. What is the surface area (in cm²) of the remaining solid?Solution
According to question: Height of cylinder = 30 cm Radius of cylinder = 5 cm Height of cone = 12 cm Radius of cone = 5 cm We know that, l2 = h2 + r2 ⇒ l2 = 122 + 52 ⇒ l2 = 144 + 25 ⇒ l = 13 cm The surface area of the remaining figure = surface area of cylinder + 2 × surface area of the cone ⇒ 2πrh + 2πrl ⇒ 2πr(h + l) ⇒ 2π × 5(30 + 13) ⇒ 430π ∴ The surface area of the remaining solid is 430π. 
What will come in place of the question mark (?) in the following series?
4, 2605, 5309, 8118, ?
117, 117, 121, 129, 141, ?
- What will come in place of the question mark (?) in the following series?
32, 45, ?, 137, 216, 317 10296/72 + 3040 = (? × 4) + 1395
38, 41, 50, ?, 158, 401Â
18, 35, 68, 117, ?, 263Â
What will come in place of the question mark (?) in the following series?
10, 135, ?, 226, 234, 235
- 741, 852, 1074, 1407, ?
9    14    38    129    ?   2705   16260
...What will come in place of the question mark (?) in the following number series?
21, 42, 67, 96, ?, 166
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