Please solve only problem no 1

problem 1-

2.A particular sale involves four items randomly selected from a large lot that is known to contain 10 percent defectives. Let Y denote the number of defectives among the four sold. The purchaser of the items will return the defectives for repair, and the repair cost is given by . Find the expected repair cost. c (y ) = 34 , y+ 2Find the symmetry and the similarity solutions for the PDE: Ofu - Or ( udru) = 0 TER, t>0