1) Number of plants in a * * * *:

48000/(0.2*0.2)= 1200000 (strain)

Because A is twice as much as B, so

Answer: 1200000/3*2=800000 (strain)

B:1200000/3 *1= 400000 (strain)

(2) Let commodity A be RMB X and commodity B be RMB 500-X..

X*70%+(500-X)90%=386

0.7X+450-0.9X=386

0.2X=450-386

X=320

500-320= 180

A commodity 320 yuan, b commodity 180 yuan.

(3) Suppose: there are x boys and x-/kloc-0 girls.

X=(X- 1- 1)*2

X=(X-2)*2

X=2X-4

2X-X=4

X=4

There are four boys and three girls.