(c) $i_{b} = \frac{5 - 0.7}{8.6} = 0.5\ mA \Rightarrow I_{c} = \beta\ I_{b} = 100 \times 0.5\ mA$ By using $V_{CE} = V_{CC} - I_{c}R_{L} = 18 - 50 \times 10^{- 3} \times 100 = 13V$
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Ph.D. in Physics with 19+ years of teaching experience.