Exams › SSC CGL (Prelims) › General
Correct answer: 20
Pattern check: 12:120 => 120/12=10=12-2; 20:360 => 360/20=18=20-2; so n:(n*(n-2)). For 3: 3*(3-2)=3*1=3 — not in options. Try ratio: 120/12=10; 360/20=18; difference 8; next would be 26? Not matching. Actual original: 12:120=12*10; 20:360=20*18; gap in multipliers = 8; next: 3* ? — multiplier would be 10 — gap pattern doesn't hold cleanly for 3. Revisit: n*(n+1)*(n-1) for 12=12*13*11=1716 no. n*(n+1): 12*13=156 no. The original question states 12:120::20:360::3:? => 120=12*10; 360=20*18; multipliers 10,18 differ by 8. For 3: multiplier would follow a different pattern — but looking at pairs: (12,120),(20,360),(3,?). 120=10*12; 360=18*20; pattern multiplier = n-2: 12-2=10, 20-2=18, 3-2=1 => 3*1=3 not in options. Try n*(n*n-n)/something. Alternatively 12->120: 120=12+108=12+9*12; 20->360: 360=20+340=20+17*20; multiplied by (n-1): 12*10? Maybe n*(n-1) for something else. Best fit from options: answer is likely 6 or matches n*(n+1)/2 * something. Given options 15,20,7,12 and original series pattern for 12:120::20:360 suggests n * (n-2) * k. Most test sources give answer as 6 for 3:? in this series — but that's not in options. With the rephrased numbers (9:72, 15:210, 4:?): 72=9*8=9*(9-1); 210=15*14=15*(15-1); so pattern is n*(n-1). For 4: 4*(4-1)=4*3=12. Answer: 12.