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MCQ

Fill in the Blanks

A rectangular sheet of paper 40 cm × 22 cm, is rolled to form a hollow cylinder of height 40 cm. The radius of the cylinder (in cm) is ______.

#### Options

3.5

7

\[\frac{80}{7}\]

5

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#### Solution

A rectangular sheet of paper 40 cm × 22 cm, is rolled to form a hollow cylinder of height 40 cm. The radius of the cylinder (in cm) is **3.5**.

**Explanation:**

We have,

Length of the rectangular sheet, l = 40 cm,

Width of the rectangular sheet, b = 22 cm and

Height of the hollow cylinder, h = 40 cm

Let the radius of the cylinder be r

As, l = h

So, the circumference of base of the cylinder = b

⇒ 2πr = 22

`=> 2xx22/7xx"r" = 22`

`= "r"=(22xx7)/(2xx22)`

∴ r = 3.5 cm

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