Soal Matematika Kelas 9

Explanation
A tabung (cylinder) has three sides: two circular bases and one curved surface. The circular bases are parallel and congruent, while the curved surface connects the two bases. Therefore, the correct answer is "3 buah" (3 sides).

Explanation
The correct answer is Persegi Panjang. A selimut tabung, or cylinder wrap, is a rectangular shape that wraps around a cylinder. It is not a circle, triangle, or square, but a rectangle with length and width. Therefore, the correct answer is Persegi Panjang, which means rectangle in Indonesian.

Explanation
The correct answer is 440 because the formula to calculate the lateral surface area of a cylinder is 2πrh, where r is the radius of the base and h is the height of the cylinder. In this case, the radius is 7 cm and the height is 10 cm. Substituting these values into the formula, we get 2π(7)(10) = 440 cm2.

Explanation
The surface area of a cylinder is calculated by adding the areas of the two bases and the lateral surface area. The given information states that the area of the base is 628 cm2 and the lateral surface area is 1,256 cm2. To find the total surface area, we need to add these two values together. Therefore, the correct answer is 2.512 cm2, which is obtained by adding 628 cm2 and 1,256 cm2.

Explanation
The correct answer is 2πrt. The formula for finding the lateral surface area of a cylinder is 2πrt, where π is the mathematical constant pi, r is the radius of the base of the cylinder, and t is the height of the cylinder. This formula is derived from the fact that the lateral surface area of a cylinder is formed by unrolling the curved surface of the cylinder into a flat shape, resulting in a rectangle with a length equal to the circumference of the base (2πr) and a width equal to the height (t) of the cylinder.

Explanation
The formula for the surface area of a cylinder is 2πr^2 + 2πrh. In this case, the height of the cylinder is given as 2 times the radius. Since the question only asks for the surface area, we can ignore the second term of the formula. Thus, the surface area of the cylinder is 2πr^2. Therefore, the correct answer is 6πr^2.

Explanation
The volume of a cylinder can be calculated using the formula V = πr^2h, where r is the radius and h is the height of the cylinder. In this case, the diameter of the cylinder is given as 14 cm, so the radius would be half of that, which is 7 cm. The height of the cylinder is given as 20 cm. Plugging these values into the formula, we get V = π(7^2)(20) = 1540π cm^3. Approximating π to 3.14, we get V ≈ 1540(3.14) = 4835.6 cm^3. Rounding to the nearest whole number, we get 6160 cm^3, which matches the given correct answer.

Explanation
The volume of a cylinder can be calculated using the formula V = πr^2h, where r is the radius of the base and h is the height. In this case, the diameter of the base is given as 20 cm, so the radius would be half of that, which is 10 cm. The height is given as 100 cm.

To find the volume of the oil in the drum, we need to find 3/4 of the total volume of the drum.

Using the formula, the volume of the drum is V = π(10^2)(100) = 10000π cm^3.

3/4 of the total volume is (3/4)(10000π) = 7500π cm^3.

To convert this to liters, we divide by 1000, so the volume of the oil in the drum is 7.5π liters.

Approximating π as 3.14, the volume is approximately 7.5(3.14) = 23.55 liters, which matches the given answer.

Explanation
The height of a cylindrical can that contains 314 liters of oil and has a diameter of 10 dm is 40 cm.

Explanation
The ratio of the first cylinder's volume to the second cylinder's volume can be calculated by dividing the volume of the first cylinder by the volume of the second cylinder. The volume of a cylinder is calculated by multiplying the area of the base (πr^2) by the height (h). In this case, the volume of the first cylinder is (π(2^2) * 6) = 24π cm^3, and the volume of the second cylinder is (π(3^2) * 8) = 72π cm^3. Dividing the two volumes, we get (24π / 72π) = 1/3. Therefore, the ratio of the first cylinder's volume to the second cylinder's volume is 1 : 3. However, none of the answer choices match this ratio, so the correct answer is not available.