A) 29.78
B) 25.93
C) 27.62
D) 32.83
Correct Answer: B
Solution :
[b] Here, Radius of cylinder=7 cm Height of cylinder=20 cm \[\therefore \] Total surface area of cylinder \[2\pi rh+2\pi {{r}^{2}}\] \[=2\times \frac{22}{7}\times 7\times 20+2\times \frac{22}{7}\times 7\times 7\] \[=880+308=1188\,\,c{{m}^{2}}\] When cylinder is cutting along height, two new Cylinders are generated-radius of new cylinder=7cm height of new cylinder=10cm \[\therefore \] Total surface area of new cylinder \[=2\pi rh+2\pi {{r}^{2}}\] \[\Rightarrow \,\,\,2\times \frac{22}{7}\times 7\times 10+2\times \frac{22}{7}\times 7\times 7\] \[\Rightarrow \,\,\,440+308\] \[=748\times 2=1496\,\,c{{m}^{2}}\] \[{{F}_{2}}\,to\,{{I}_{2}}\]Total surface area of two new cylinders \[=748\times 2=1496\,\,c{{m}^{2}}\] \[\therefore \]Percentage increase in surface area \[=\left( \frac{(1496-\,1188)}{1188}\times 100 \right)%=25.93%\]
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