1, 5 is less than 8 (37.5)%, and 8 is more than 5 (60)%.

2. Uncle Wang's house was renovated with a planned investment of 80,000 yuan, and the actual investment was 1.2 million yuan, which was (50)% overrun.

There are 900 students in the central primary school, of which 60% are boys and 540 are boys.

4.2 100kg rapeseed can extract 882kg oil, and the oil yield of rapeseed is (42%).

Second, the application problem.

1, a pair of shoes, now the price is 340 yuan, which is cheaper than the original price 15%. What is the original price?

340( 1- 15%)= 400 (yuan)

A: The original price is 400 yuan.

The grain processing factory planned to process 7500 tons of grain last year, but actually processed 8400 tons. How much more food was actually processed than planned?

(8400-7500)÷7500= 12%

A: The grain actually processed is more than planned 12%.

3. Have a set of home appliances. A TV costs 2000 yuan, the price of power amplifier is 80% of that of TV, and the price of speaker is 20% more expensive than that of power amplifier. How much can I bring with me to buy this home appliance combination?

2000×80%= 1600 (yuan)

1600× (1+20%) =1920 (yuan)

2000+1600+1920 = 5520 (yuan)

A: You must bring at least 5520 yuan to buy this home appliance combination.