Group A
Money spent by Person 1 = £500
Money spent by Person 2 = £600
Money spent by Person 3 = £900
Money spent by Person 4 = £450
Sum of money spent by group A = £2,450
Average money spent by group A = 
⇒ Average money spent by group A = £612.5
Group B
Money spent by Person 1 = £700
Money spent by Person 2 = £500
Money spent by Person 3 = £680
Money spent by Person 4 = £500
Sum of money spent by group B = £2,380
Average money spent by group B = 
⇒ Average money spent by group B = £595
Hence, Group B had lower average spend.