Understanding galaxy evolution from spectra is challenging due to intertwined properties. We are using synthetic spectra from stellar population models in conjunction with more than 377 galaxies spectra at redshifts of 0.9 to 1.2, from VIMOS and FORS2. Using Bayesian techniques, we are determining the galaxy properties such as mass-to-light ratios, metallicity and age from a recent star burst. We start by shifting the observed optical spectra to their rest-frame, then convolving the model spectra to the instrumental spectral resolution of the observed spectra. Finally, we conduct a Chi square fitting, extract the likelihood, and build a posterior probability distribution function for the required set of parameters. We will report ongoing efforts to determine these properties which will help us understand how galaxies evolve.