Answer
a) each number is divided by 2
b) 4.5
Work Step by Step
a) the relationship between 144 and 72 is either minus 72 or divide by 2. The next pair is 72 and 36. The relationship is either minus -36 or divide by 2. The only common relationship is divide by 2.
b) We follow the pattern: 144, 72, 36, 18, 9, 4.5
4.5 is the first non-integer in the sequence.
