please help me solve this question

Q 1. Consider the regression line given by E(Y) = BXi, i = 1, 2, ..., n. a. Find the least square estimate of 3. b. Assume that the error term & are independent /V(0, o') and o is known. State the likeli- hood function for the n sample observation Y and obtain the maxmum likkelihood estimator of B. Is it the same as the least squares estimator? c. Find E{B} d. Find of {B}