Soal Matematika Kelas 9

1. Bentuk selimut tabung adalah ....

Lingkaran

Segitiga

Persegi

Persegi Panjang

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 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.

2. Luas selimut tabung yang memiliki jari-jari alas 7 cm dan tinggi 10 cm adalah ....cm²

110

220

330

440

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 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.

3. Rumus luas selimut tabung adalah ....

πrt

2πrt

3πrt

4πrt

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 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.

4. Banyak sisi pada tabung adalah ....

1 buah

2 buah

3 buah

4 buah

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

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).

5. Jika sebuah tabung memiliki luas alas 628 cm² dan luas selimut 1.256 cm2 maka luas permukaan tabung tersebut adalah ....cm²

1.884

2.512

3.140

5.024

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 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.

6. Tinggi suatu kaleng yang berbentuk tabung yang berisi minyak 314 liter dan berdiameter 10 dm adalah … cm

25

30

35

40

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

Explanation

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

7. Sebuah drum berbentuk tabung dengan diameter alas 20 cm dan tinggi 100 cm. Bila 3/4 bagian dari drum berisi minyak , banyak minyak di dalam drum tersebut adalah....

22,55 liter

23,55 liter

24,55 liter

25,55 liter

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 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.

8. Sebuah Tabung berdiameter 14 cm dan tinggi 20 cm. Volume tabung tersebut adalah ....

6.160 cm3

3.080 cm3

880 cm3

616cm3

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 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.

9. Sebuah tabung mempunyai jari-jari r cm dan tingginya 2 kali panjang jari-jari, maka luas permukaan tabung tersebut adalah ….cm²

2πr2

4πr2

5πr2

6πr2

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 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.

10. Diketahui ada dua buah tabung. Jika tabung pertama berjari-jari 2 cm dan tingginya 6 cm, sedangkan tabung kedua berjari-jari 3 cm dan tingginya 8 cm. Perbandingan kedua tabung adalah ....

1 : 8

1 : 12

1 : 16

1 : 24

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.

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.