New radius is 1.1r, making squared radius 1.21r². For unchanged volume, the new height must be h / 1.21 ≈ 0.8264h. Thus, height decreases by approximately 17.36%, meaning x ≈ 17.36 or 2100/121%.
Class 9 Chapter 14 Math of Space Surface Area and Volume solutions
Class 9 Ganita Manjari Part 2 book questions with solutionsradius of the base of a cylinder is increased by 10%.
Let original radius and height be r and h, so initial volume is V = πr²h. The increased radius is r’ = 1.1r. Since the volume remains unchanged, π(1.1r)²h’ = πr²h, giving 1.21h’ = h or h’ = h / 1.21. The percentage decrease in height is x = [(h − h’) / h] × 100 = [1 − (1 / 1.21)] × 100 = 2100/121% ≈ 17.36%.
For more NCERT Solutions of Class 9 Maths Ganita Manjari Part 2 Chapter 14 Math of Space: Surface Area and Volume Question Answer (2026-27)
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