Multiple choice

Each of the following number series one number is wrong. Find out the odd number. 150 75 50 40 30 25

  1. 75

  2. 150

  3. 25

  4. 50

  5. 40
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Pattern: 150÷2=75, 75÷1.5=50, 50÷1.25=40, 40÷1.33≈30, 30÷1.2=25. Actually, check: 150→75 (÷2), 75→50 (÷1.5 or ×2/3), 50→40 (÷1.25 or ×4/5), 40→30 (÷1.33 or ×3/4), 30→25 (÷1.2 or ×5/6). Pattern is dividing by (n+1)/n: ÷2/1, ÷3/2, ÷5/4, ÷4/3 (should be ÷4/3=÷1.33 giving 30, correct from 40), then ÷6/5=÷1.2. The series is consistent - 40 doesn't fit? Wait, checking 50÷1.25=40, then 40÷1.33=30... the divisors are 2, 1.5, 1.25, 1.2... which are 2/1, 3/2, 4/3, 5/4, 6/5. But 50→40 is ×0.8=4/5, should be 4/3=1.33. So 40 should be 50÷(4/3)=37.5, not 40. Actually, let me re-verify: 150÷2=75, 75÷1.5=50, 50÷1.333...=37.5 not 40, 37.5÷1.25=30, 30÷1.2=25. So 40 is wrong.

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