Question

a project can completed in15 days if 24 member work 8 hour a day if there are 20 member available to do the same project 16 days then how many hour do they need work in a day

Answer 1

15×24×8 = 20×16×X

15x24x8/ 20×16 = X

15 = X answer

Answer 2

member                                  hours                             portion of project
24                                           8 x 15                                  1(whole)
1                                              8 x 15                               1/24
1                                              1                                      1 / 24 x 8 x 15
20                                            1                                      20 / 24 x 8 x15
20                                            16 x h                           16h x 20 / 24 x 8 x15

now to complete the project
16h x 20 / 24 x 8 x 15 = 1
h  =  3 hrs per day