(20 14? In recent years, smog weather has occurred frequently in many provinces and cities in China. In order to enhance citizens' awareness of environmental protection, a city collected N names for t

(20 14? In recent years, smog weather has occurred frequently in many provinces and cities in China. In order to enhance citizens' awareness of environmental protection, a city collected N names for the whole city. Solution: Solution: (1) From the meaning of the question:

Number of people in the second group: 35=5×0.07n,

Get: n= 100,

Therefore, the organization has 100 people.

(2) The number of people in the third group is 0.3× 100=30,

The number of the fourth group is 0.2× 100=20.

The number of people in the fifth group is 0./kloc-0 /×100 =10.

There are 60 volunteers in groups 3, 4 and 5.

∴ Using stratified sampling method at 60,

Six volunteers were selected from a total of six volunteers, and the number of people in each group was:

The third group: 3060× 6 = 3;

The fourth group: 2060× 6 = 2; ?

The fifth group: 1060× 6 = 1.

Therefore, 3 people, 2 people and 1 person should be selected from groups 3, 4 and 5 respectively.

(3) Remember that the third group of three volunteers is A 1, A2, A3, the fourth group of two volunteers is B 1, B2, and the fifth group of 1 volunteers is C 1.

Then two of the six volunteers are:

(A 1，A2)、(A 1，A3)、(A 1，B 1)、(A 1，B2)、(A 1，C 1)、(A2，A3)、(A2，B 1)、(A2，B2)、(A2，C 1)、(A3，B 1)、(A3，B2)、

(A3, C 1), (B 1, B2), (B 1, C 1), (B2, C 1), * * there are 15 kinds.

Among them, the third group A 1, A2 and A3 have three volunteers, and at least one volunteer is selected:

(A 1，A2)、(A 1，A3)、(A 1，B 1)、(A 1，B2)、(A 1，C 1)、(A2，A3)、(A2，B 1)、(A2，B2)、(A2，C 1)、(A3，B 1)、(A3，B2)、

(A3, C 1), there are 12 kinds of * *.

Then the probability that at least one volunteer in the third group is drawn is p = 12 15 = 45.