Answer:
1.5
Step-by-step explanation:
In the given series 3 4.5 6 7.5 9 10.5
[tex]a_{1}=3[/tex] , [tex]a_{2}=4.5[/tex] , [tex]a_{3} =6[/tex]
As the series is arithmetic and in arithmetic series common difference is,
[tex]d=a_{2}-a_{1}[/tex]
[tex]d_{1} =4.5-3=1.5\\[/tex]
[tex]d_{2} =6-4.5=1.5[/tex]
So, common difference is 1.5
