bonjour,

1)

p1 = p2/2

=> p2 = 2p1

p1 = p3/3

=> p3= 3p1

p1 = p4/4

=> p4= 4p1

p1 = p5/5

=> p5= 5p1

p1 = p6/6

=> p6= 6p1

2)

p1 +p2 +p3 +p4+p5 +p6=1

p1 +2p1+3p1+4p1+5p1+6p1 =1

21p1 =1

p1 = 1/21

3)

a)

nombre pair

{2;4;6  }

2/21+4/21+6/21 = 12/21=4/7

b)

multiple de 3

{3;6}

3/21 + 6/21 = 9/21=3/7