In designing an iron gril a black smith needed 70 rings with radius of

1.	In designing an iron gril a black smith needed 70 rings with radius of 7cm each. Find how much length of the rod he required, if the wastage is 20 cm.
Answer» Given radius of the ring r = 7 cm Circumference of the ring C = 2πr = 2 x \(\frac{22}{7}\) x 7 = 44 cm Length of rod required to make one ring = 44 cm Length of rod required to make 70 rings = 44 x 70 = 3080 cm Wastage = 20 cm Required length of rod to make 70 rings = 3080 + 20 = 3100 cm

In designing an iron gril a black smith needed 70 rings with radius of 7cm each. Find how much length of the rod he required, if the wastage is 20 cm.

Answer»

Given radius of the ring r = 7 cm

Circumference of the ring C = 2πr

= 2 x \(\frac{22}{7}\) x 7 = 44 cm

Length of rod required to make one ring = 44 cm

Length of rod required to make 70 rings

= 44 x 70 = 3080 cm

Wastage = 20 cm

Required length of rod to make 70 rings = 3080 + 20 = 3100 cm