Pembahasan Ujian PAI: A30 – No. 32 – Maret 2016

• TC = 50 + 20 Q
• Fungsi permintaan pasar : P = 100 – 4.Q
• Pajak = r = Rp. 8,- /satuan
• Sebelum kena pajak Q = 10

• \(TR = PQ\)
• \({\pi _{\max }} = TR – TC\)
• \(MR = MC + r\)

Setelah Pajak:
\(TR = PQ = (100 – 4Q)Q = 100Q – 4{Q^2}\) \(MR = \frac{{dTR}}{{dQ}} = \frac{{d(100Q – 4{Q^2})}}{{dQ}} = 100 – 8Q\) \(MR = \frac{{dTC}}{{dQ}} = \frac{{d(50 + 20Q)}}{{dQ}} = 20\) \(MR = MC + r\) \(100 – 8Q = 20 + 8\) \(Q = 9\) \(P = 100 – 4(9) = 64\) \(TR = PQ = (100 – 4(9))(9) = 576\) \(TC = 50 + 20(9) = 230\) \({\pi _{\max }} = TR – TC = 576 – 230 = 346\)

Setelah pajak:
P naik sebesar 4
Q turun sebesar 1
Profit (\({\pi _{\max }}\)) turun sebesar 4