The sum of the radius of the base and the height of a closed solid cylinder is 12.5 cm. If the total surface area of the cylinder is 275 cm² , then its radius is:

(Take $π =\frac{22}{7}$)

3.5 cm

We know that,

Total surface area of a closed cylinder = 2πR (H + R)

Given,

Radius + Height = 12.5 cm 

Total surface area of cylinder = 275 cm²

So,

= 275 = 2 × \(\frac{22}{7}\)× R × (12.5) 

= R = (275 × 7 × 10) × \(\frac{1}{2 × 22 × 125  }\)

= R = 3.5