1) Which spectral type has the hottest stars? Which has the coolest stars?

2) As we go from cooler stars to hotter stars, what happens to the Main Sequence life span? 

3) How do we know that a sample is similar to the whole population?

4)  Extra Credit: The “Thick Disk” population described in the lab manual may have been created when the Milky Way absorbed another small galaxy orbiting around it and creating many new stars in the process. Compare the Thick Disk histogram in the manual to the spectral types described in Table 2 to give an estimate of how long ago this merger may have taken place. Explain your answer.