In the series given below, one number is wrong. Find the wrong number.
11, 15, 20, 26, 33, 40, 50
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 40
Look at the difference between each pair of terms; they should grow by 1 each time:
\(15-11=4\), \(20-15=5\), \(26-20=6\), \(33-26=7\)
The next difference should be 8: \(33+8=41\), but the series has 40
Then \(41+9=50\), which matches the last term
All the other terms fit if the sixth term is 41. So 40 is the wrong number.