One is that the second term of the arithmetic sequence is 2.8, and the third term is 3.1. Find the 15th term of the arithmetic sequence

A:
If the tolerance is D, then:
a3-a2=d=3.1-2.8=0.3
a1=a2-d=2.8-0.3=2.5
a15=a1+14d=2.5+14*0.3=6.7
So item 15 is 6.7

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