coroana)))))))))))))))

Răspuns:
Explicație pas cu pas:
In suma sunt 49-30+1 = 20 termeni
1/49+1/49+...+1/49 < 1/30+1/31+...+1/49 <
< 1/30 +1/30 +...+1/30
20/49 < 1/30+1/31+...+1/49 < 20/30 = 2/3
1/3 < 20/49, sau 49 < 60, deci :
1/3 < 1/30+1/31+...+1/49 < 2/3