A very long line charge (λ1 = +5.20 10-6 C/m) lies along the central axis of a very long thin-walled cylinder of radius R = 6 cm and λ2 = -7.50 10-6 C/m.

a.) Find the electric field at radial distance r = 4.1 cm from the common central axis.

Found answer to be E = 2.28x10^6

b.) Find the electric field at r = 7.1 cm.

E = ?

I need help on B. I can't seem to get it. The thin-walled cylinder is a bit confusing. Any help would be appreciated. Thanks!