No of ways in which the 3 correct envelopes can be selected= 7C3 =35 Derangement of the remaining 4 envelopes & letters = 9 (derangement value for 4 is 9) Total No of ways of arrangement = 9 x 35= 315. Example 2: In how many ways can you form a dancing couple from 3 boys and 3
B52club
Guangzhou Astrum New Material Co.,ltd
Front Desk
Isya
Tỷ Lệ Kèo Nhà Cái
Esteemed Electrics
Gen88hdecom
Sin88 Health
Farmers Insurance - Christopher Evans
Doc Savage Heating And Air Conditioning, Inc.