Answer:
70
Step-by-step explanation:
[tex]a_1[/tex] = First term = [tex]\dfrac{1}{3}[/tex]
[tex]d[/tex] = Common difference = [tex]\dfrac{2}{3}-\dfrac{1}{3}=\dfrac{1}{3}[/tex]
[tex]n[/tex] = Number of terms = 20
Sum of arithmetic progression is given by
[tex]S=\dfrac{n}{2}[2a_1+(n-1)d]\\\Rightarrow S=\dfrac{20}{2}\times (2\times \dfrac{1}{3}+(20-1)\dfrac{1}{3})\\\Rightarrow S=70[/tex]
The sum of the first 20 terms of the arithmetic sequence is 70.
