In order to help a dry area solve the drinking water problem, a mineral water company took the initiative to produce 300 tons of mineral water for the dry area.

(1) solution: suppose the original plan was to produce x tons of mineral water every day.

Solve it and get: x=50, so it is practical? 50× (1+20%) = 60 tons

(2) Solution: If there are Y Type A cars, there are (16-y) Type B cars, which are derived from the meaning in the question:

20y+ 15( 16-y)≥300

500y+300( 16-y)≤7800

To solve this problem, you must:

12≤y≤ 15

And y is an integer.

Y can be 12, 13, 14, 15.

There are four schemes.

① 12 A car? Four b-cars?

② 13 A car? Three b-cars.

314 a car? Two b-cars.

415 a car? 1 B car

(3) Solution: Let w be the total transportation cost, then:

w=500y+300( 16-y)

That is w=200y+4800.

The smaller y, the lower the cost.

∴y takes 12 as the minimum value.

In other words, the cost of the first scheme is lower.