provide me solution as soon as possible thanks

Task 4 4 In a city with a constant population of 10000 an advertising agency has been tasked with creating an advertisement campaign for a new product. The campaign ensures that the rate of change (with respect to {) of Individuals z in the population that have heard of the product at time t (where t is measured in days) is equal to half of the individuals in the population that so far have not heard about the product. How long does it take before 95% of the population have heard about the product if we assume that z (0) = 100