Power Calculation of an Amplifier
This stinks.

The two 150k\$\Omega\$ resistors bias the transistor at a 14\$\mu\$A base current. At an \$H_{FE}\$ of 15000 that's 210mA quiescent current. So far so good, if it weren't that that DC current flows through the speaker. You don't do that. Speakers should only get AC. Anyway, your quiescent point will be at 3.3V, which gives you a maximum \$V_P\$ of 1.7V, or 175mW RMS in 8\$\Omega\$. 

The 10\$\mu\$F cap has an impedance of 16\$\Omega\$ at 1000Hz. With two base-emitter resistances of 26\$\Omega\$ that's a 4.4mA peak base current at 300mV. Even at the lowest specified \$H_{FE}\$ of 4000 that would give 17.6A collector current. With the appropriate power supply that gives 2500W in 8\$\Omega\$. The 5V supply and the 1.5V \$V_{CE(SAT)}\$ will limit that to 440mA, but it does mean that the transistor goes completely in saturation.  

edit (after changes in schematic)
The changes don't make much difference. Base current is now 5.9\$\mu\$A, collector current 89mA, which, with a 16\$\Omega\$ speaker gives a quiescent point at 3.6V. With an 8\$\Omega\$ speaker it's 4.3V. The results are the same.