Weights for Surveys

Just wondering if someone can provide some help,

Confused on a question trying to work out weight without a population size, could someone explain what the weights would be for the two scenarios below.

a) A stratified sample consisting of 180 people of three ethnicities, 60 Asians, 60 Europeans, and 60 Africans. If the populations of asians europans and africans are the same what would the weight be for each data-point. Is it 1 as all points contribute equally?.

b) Would this weight be the same if the 180 were a simple random sample?