1) cost per child = 400
2) cost per child for these additional 20 children = 460/ 20 = $ 23
3) the average cost per child = (400 + 460)/ 21 = 860 / 21 = $ 40. 952
4) The above result show that the cost of polio vaccine is less which is only $23. But the setting up immunization program & other necessary associated works have adds up to a higher cost of $ 40. 952. This can be reduced if more nos. of children are involved in the immunization program.
Also, the cost of setting up immunization program will be same for one child or more than one. Only the cost of polio vaccine will vary when the nos. of participating will increase.