(2)Y is greater than or equal to 24000. namely

6x * 150+5 *(20-x)* 260≥24000

900x+26000- 1300x≥24000

2000 ≥400 times

5≥x

In other words, no more than five people can make a part.

Then manufacturing part B is 20-5= 15. At least 15 workers should be sent to manufacture part B.

2. We assume that the students answered the X question correctly.

6x-( 16- 1-x)*2≥60

8x≥90

x≥ 1 1.25

Take the integer as 12, that is, at least answer 12 correctly.

3, set the number of students x, dormitory number y.

Then the system of equations: {4y+20=x

{8Y>x> is eight years old

8y & gt4y+20 & gt； 7y

20/3 >y> v

Because y is an integer, Y=6.

So X=44.

There are 44 students and 6 dormitories.

Hard-made mathematical symbols are particularly difficult to type, please adopt them.