Complete the series:
10.5, 7.5, ______, 3.0, 1.5, 0.5
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 5.0
The amount taken away falls by 0.5 at each step. The known differences at the two ends show it: 3.0 at the start, then 1.5 and 1.0 at the end.
\(10.5-3.0=7.5\)
\(7.5-2.5=5.0\) (the missing term)
\(5.0-2.0=3.0\)
\(3.0-1.5=1.5\)
\(1.5-1.0=0.5\)