In a neutron guide, instrument IN3 is located at the end of a neutron guide, and the incident neutron flux at its monochromator is assumed to be 0.9 times of the flux I(20) at IN20 (the guide does lose some neutrons, not as perfect as an optic fiber). Now if the neutron guide has not been invented, and the same pipe tube as at IN20 is used, what would be the flux at IN3 in terms of I(20)?