Answer:
2
Step-by-step explanation:
An arithmetic progression with first term a and common difference d has the following first 6 terms:
a, a + d, a + 2d, a + 3d, a + 4d, a + 5d
We are given a = 1 and a + 5d = 11.
1 + 5d = 11
5d = 10
d = 2
Answer: The common difference is 2.
