A) 6 cm
B) 3.2 cm
C) 3 cm
D) 3.5 cm
Correct Answer: C
Solution :
Let the original radius be r cm. According to the question, \[\pi \,\,{{(r+1)}^{2}}-\pi {{r}^{2}}=22\] \[\Rightarrow \] \[\pi \,\,({{r}^{2}}+2\,r+1-{{r}^{2}})=22\] \[\Rightarrow \]\[(2\,r+1)\times \frac{22}{7}=22\]\[\Rightarrow \]\[2\,r+1=\frac{22\times 7}{22}=7\] \[\Rightarrow \] \[2\,r=7-1=6\]\[\Rightarrow \]\[r=\frac{6}{2}=3\,\,\text{cm}\]
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