Hundreds of millions of supermarkets have three kinds of fruit juices in large, medium and small packages. Dandan wants to prepare 300mL juice for each of the eight students who come to visit at home. How to buy the most cost-effective? Large bottles per bottle15.4÷1000 = 0.0154 (yuan),

8÷÷÷500 per bottle = 0.016 (yuan),

Small bottles are 3.4 ÷ 200 per bottle = 0.017 (yuan),

So it is cheaper to buy a big bottle as much as possible;

A * * * Drinks needed: 300×8 = 2400(ml)；);

You can buy two large bottles, leaving 400 ml. If you buy 1 bottle, you need 8 yuan. If you buy 2 vials, you need 3.4×2=6.8 yuan.

So buying two large bottles and two small bottles is the most cost-effective, and it costs:

15.4×2+3.4×2

=30.8+6.8

=37.6 (yuan)

Answer: It is the most cost-effective to buy two large bottles and two small bottles, 37.6 yuan.