93.1k views
1 vote
What is the sum of the first 27 terms of the sequence 2.5+5.5+8.5+11.5?

User Gandalf
by
7.7k points

1 Answer

2 votes
It's an arithmetic sequence with:

a_1=2.5\\\\d=5.5-2.5=3
The formula of the sum of the n terms of an arithmetic sequence:

S_n=(2a_1+(n-1)d)/(2)\cdot n
Substitute:

n=27;\ a_1=2.5;\ d=3\\\\S_(27)=(2\cdot2.5+(27-1)\cdot3)/(2)\cdot27=(5+26\cdot3)/(2)\cdot27=1,120.5
User Tgr
by
7.8k points

No related questions found

Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.

9.4m questions

12.2m answers

Categories