Assume that the galaxy is 10 gyr old, the rate of star formation in the past was proportional to e^-t/t, where t is time since the galaxy formed and t = 3 gyr. and stellar lifetimes are given by t(m) = 10 gyr (m/msun)^-3. calculate the fractions of all (a) 2msun and (b) 5msun stars ever formed that are still around today.

The frequency of a tuning fork can be found by the method shown. a long tube open at both ends is submerged in a beaker of water, and the vibrating tuning fork is placed near the top of the tube. the length l of the air column is adjusted by moving the tube vertically. the sound waves generated by the fork are reinforced when the length of the air column corresponds to one of the resonant frequencies of the tube. the smallest value for l for which a peak occurs in sound intensity is 7 cm. l what is the frequency of the tuning fork? the speed of sound in air is 345 m/s. answer in units of hz