UPSC CDS I 2025 Mathematics Paper

Outer dimension = internal +2× side thickness ( for L and B ), depth adds bottom thickness
Volume of material = Volume ‌outer ‌− Volume ‌‌inner ‌
1cm3=10−6m3; Mass = Density × Volume
Calculations:
⇒ Outer L =14+2×0.5=15cm
⇒ Outer B =10+2×0.5=11cm
⇒ Outer D=8+1=9cm
⇒ Volume ‌outer ‌=15×11×9=1485cm3
⇒ Volume ‌inner ‌=14×10×8=1120cm3
⇒ Volume ‌material ‌=1485−1120=365cm3
⇒ Volume (m3)=365×10−6=3.65×10−4m3
⇒ Mass =2000×3.65×10−4=0.73kg=730gm
Volume of water = Volume ‌inner ‌=14×10×8=1120cm3=1120×10−6m3
Weight of water =1000×1120×10−6kg=1.12kg
Total weight of the box with water =0.73kg+1.12kg=1.850kg
∴ The correct answer is option 1 .