Land area: 1500 km2; Green area: 450 square kilometers; Green coverage rate: 38%; Per capita public green area: 7.2 square meters.

(1) green rate = green area ÷ land area 450 ÷ 1500 = 0.3 = 30%.

The greening rate in this urban area is 30%, which is not up to standard.

(2)(7.5-7.2)÷7.5=0.04=4%

The per capita public green space in this city is 4% less than the national standard.

(3) If we want to answer this question by combining the land area and green coverage rate of the city, there will be mistakes. Assuming that the green coverage rate of residential area is at least X, the relationship between land area and urban green coverage rate is 36% = (1500× 38%+x) ÷ (1500+0.012).

The results show that x is negative, so it is absolutely unnecessary to increase the green coverage area of the community, and the urban green coverage rate can reach the standard.

If we look at the residential land planning independently, we can get the relationship: X= 12000×36%=4320m?

The green coverage area of the community is at least 4320 square meters.

I see. Welcome to point out the mistakes.