Consider the following set of ages of students is a college seminar.

Answer:
1) [tex]\sum\limits_{i=2}^{6}x_{i}=116[/tex]
2) [tex]\sum\limits_{i=1}^{4}x_{i}=87[/tex]
Step-by-step explanation:
Given that [tex]x_{1}=21,x_{2}=23,x_{3}=22,x_{4}=21,x_{5}=24,x_{6}=26,x_{7}=28[/tex]
1) Given that [tex]\sum\limits_{i=2}^{6}x_{i}[/tex]
To find [tex]\sum\limits_{i=2}^{6}x_{i}[/tex]
Expanding the sums below to solve it
[tex]\sum\limits_{i=2}^{6}x_{i}=x_{2}+x_{3}+x_{4}+x_{5}+x_{6}[/tex]
[tex]=23+22+21+24+26[/tex] (adding the terms )
[tex]=116[/tex]
Therefore [tex]\sum\limits_{i=2}^{6}x_{i}=116[/tex]
2) Given that [tex]\sum\limits_{i=1}^{4}x_{i}[/tex]
To find [tex]\sum\limits_{i=1}^{4}x_{i}[/tex]
Expanding the sums below to solve it
[tex]\sum\limits_{i=1}^{4}x_{i}=x_{1}+x_{2}+x_{3}+x_{4}[/tex]
[tex]=21+23+22+21[/tex] (adding the terms )
[tex]=87[/tex]
Therefore [tex]\sum\limits_{i=1}^{4}x_{i}=87[/tex]