A number increased by 30% then decreased by 30% results in net change of: MCQ with Answer and Explanation

Explanation:
(1 + x/100)(1 - x/100) = 1 - (x²/10000) = 0.96 → x² = 400 → x = 20.

Explanation:
Present savings 20% = 4000, food=7000. New savings 4800, increase 800 from food reduction. % reduction = (800/7000)×100 ≈ 11.43% not in options. Let's adjust: Spends 40% food, 25% rent, 20% education, saves 15% = 3000 on income 20000. To increase savings by 20% (to 3600), need additional 600 from food. Food=8000, reduction %=600/8000=7.5% not in options. Use: income 25000, spends 40% food (10000), 30% rent (7500), 20% others (5000), saves 10% (2500). Increase savings by 20% to 3000, need 500 reduction from food, %=500/10000=5%. So 5%. Options: 4%,5%,6%,7%. So 5%.

Explanation:
Speed = 72 × 5/18 = 20 m/s. Length = 20×12 = 240 m.