score:6
From the account of the spies entering Canaan, Joshua is identified as an Ephraimite (Tribe of Joseph, half-tribe of Ephraim):
from the tribe of Ephraim, Hoshea the son of Nun; - Numbers 13:8 ESV
and in case of any doubt that Hoshea son of Nun is one and the same as Joshua son of Nun:
And Joshua the son of Nun and Caleb the son of Jephunneh, who were among those who had spied out the land, tore their clothes - Numbers 14:6 ESV
-- makes it clear that it's the same guy.