Answer Key & Solutions
Q1: 24 — Factors of 48: 1,2,3,4,6,8,12,16,24,48. Factors of 72: 1,2,3,4,6,8,9,12,18,24,36,72. Greatest common factor = 24.
Q2: 12 — LCM(4,6): multiples of 4: 4,8,12,16… multiples of 6: 6,12,18… First common multiple = 12.
Q3: 105 — 40% of x = 56 → x = 140. Then 75% of 140 = 0.75 × 140 = 105.
Q4: $74.80 — Discounted: 80 × 0.85 = $68. With tax: 68 × 1.10 = $74.80.
Q5: 5 — 5x − 2x = 12 + 3 → 3x = 15 → x = 5.
Q6: 17 — f(−2) = 3(4) − 2(−2) + 1 = 12 + 4 + 1 = 17.
Q7: 2 — 2x + 5 = −x + 11 → 3x = 6 → x = 2.
Q8: 6x⁵y⁶ — Multiply coefficients: 2×3=6. Add exponents: x³⁺²=x⁵, y²⁺⁴=y⁶.
Q9: 162 — 2(2w + w) = 54 → 6w = 54 → w = 9, l = 18. Area = 9 × 18 = 162 cm².
Q10: 50 — C = 180 − 47 − 83 = 50°.
Q11: 14π — πr² = 49π → r² = 49 → r = 7. C = 2π × 7 = 14π cm.
Q12: 12 — a² + 5² = 13² → a² = 169 − 25 = 144 → a = 12.
Q13: 14 — Sorted: 12, 13, 14, 14, 15, 16. Median = (14+14)/2 = 14.
Q14: 3/10 — P(blue) = 3/(5+3+2) = 3/10. Already simplified.
Q15: 81 — Total = 82 × 5 = 410. Sum of 4 scores = 78+85+90+76 = 329. Fifth = 410 − 329 = 81.
Q16: 140 — 5/2 = 350/x → x = (350 × 2)/5 = 140 g.
Q17: Same speed (60 mph) — Train A: 240/4 = 60 mph. Train B: 300/5 = 60 mph. They are equal.
Q18: 12/5 (2.4 hours) — Rate = 1/6 + 1/4 = 2/12 + 3/12 = 5/12. Time = 12/5 = 2.4 hours.
Q19: 6 — n + p = 10, 3n + 1.5p = 24 → multiply first by 1.5: 1.5n + 1.5p = 15 → subtract: 1.5n = 9 → n = 6.
Q20: 720 — Original h = 360/(10×6) = 6 cm. New h = 12. New volume = 10 × 6 × 12 = 720 cm³.