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A thread is wound 200 times round a reel of diameter 5 cm. Use the value 3 for it to find the approximate length of the thread in metres.

A thread is wound 200 times round a reel of diameter 5 cm Use the value 3 for it to find the approximate length of the thread in metres class=

Respuesta :

Answer:

Length of the thread = 30 metres

Step-by-step explanation:

Length of the thread in one round of a reel = Circumference of the reel

                                                                    C = [tex]2\pi r[/tex]

Since radius of the reel = [tex]\frac{\text{Diameter}}{2}[/tex]

                                       = [tex]\frac{5}{2}[/tex]

                                       = 2.5 cm

Circumference of the reel = 2(π)(2.5)

                                           = 5π

                                           = 5×3

                                           = 15 cm

Length of the thread wound in one round around the reel = 15 cm

Since, thread is wound 200 times round a reel, length of the thread

= 200 × 15                                                      

= 3000 cm

30 metres

Therefore, Option (B) will be the answer.