Please help me answer/perform the following with complete solution, I am really bad at STATS :

3. A stratified sample of size n = 120 is to be taken from a population of size N = 8000, which consists of three strata of size N = 4000, N = 2400 and N = 1600. If the allocation is to proportional, how large a sample must be taken from each stratum? 5. A study was conducted to find the distribution of fraternity members in colleges of a university. If the total population is 12,000 and the students are distributed by college as follows: Liberal Arts = 1,200; Commerce = 4,950; Engineering = 2,700; Science = 2350 and Education = 800, determine the sample using a) Simple random b) Stratified random