Three people independently each think of an integer in the set {1,2,3,4,5,6,7}.

Question

Please help I have no idea how to do this question.  

 

Three people independently each think of an integer in the set {1,2,3,4,5,6,7}. Find, in fractional form, the probability that the sum of the three integers selected is more than 15  

Answer 1

THere are 7 x 7 x 7 = 343 possible selections.

 

777    767     757   747    737   727

776    766     756   746    736   

775    765     755   745

774    764     754  

773    763

772

 

 

677  667  657  647  637

676  666  656  646

675  665  655

674  664

673

 

577  567  557  547

576  566  556

575  565

574

 

477   467  457

476   466

475

 

377  367

376

 

277

 

count them all and divided by 343.

BUT one more thing.....

Does the order matter? FOr example, is 667 the same as 766 the same as 676?

If so, then you must remove the duplicates from these lists.