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1. A township originally planned to afforest 12 hectares last year, but actually afforested 14 hectares. How many percent more than the original plan? 2. During the "Eleventh Five Year Plan" period, the Xiaojun family planned to spend 2000 yuan, and the actual consumption was 1800 yuan. How much less was the actual consumption than the planned consumption? 3. Guangming Village has 121 units per 100 households this year, an increase of 66 units compared with last year. How much has this year increased compared with last year? 4. Xiao Ming's mother's monthly salary is 2000 yuan. In the past, her monthly salary was 1800 yuan. Now, how much higher than the original salary? 5. On the morning of October 1, 2009, 240 people in Grade 5 watched the 60th anniversary of the National Day parade on TV, and 300 people in Grade 6 watched the 60th anniversary of the National Day parade?
Application of percentage in practical problems of preparatory mathematics
1. A township originally planned to afforest 12 hectares last year, but actually afforested 14 hectares. How many percent more than the original plan?
（14-12）÷12
=2÷12
=1/6
≈16.7%
2. During the "Eleventh Five Year Plan" period, the Xiaojun family planned to spend 2000 yuan, and the actual consumption was 1800 yuan. How much less was the actual consumption than the planned consumption?
（2000-1800）÷2000
=200÷2000
=10%
3. Guangming Village has 121 units per 100 households this year, an increase of 66 units compared with last year. How much has this year increased compared with last year?
66÷（121-66）
=66÷55
=1.2
=120%
4. Xiao Ming's mother's monthly salary is 2000 yuan. In the past, her monthly salary was 1800 yuan. Now, how much higher than the original salary?
（2000-1800）÷1800
=200÷1800
=1/9
≈11.1%
5. On the morning of October 1, 2009, 240 people in Grade 5 watched the 60th anniversary of the National Day parade on TV, and 300 people in Grade 6 watched the 60th anniversary of the National Day parade?
（300-240）÷300
=60÷300
=20%
Application of percentages in sixth grade
Lao Zhang invested in the tea and silk businesses. Three months later, he got 2100 yuan each in the two businesses. He earned 25% in the tea business and lost 25% in the silk business
(1) Did he lose or earn in the end? How many yuan did he lose or earn?
(2) He will continue to invest the existing funds in the tea business. How many yuan can he earn in one year?
(1) The cost of tea is x yuan (1 + 25%), x = 2100, x = 1680, profit is 2100-1680 = 420, the cost of silk is y yuan (1-25%), y = 2100, y = 2800, loss is 2800-2100 = 700, because 700 ＞ 420, loss is 700-420 = 280 (2) the existing capital is 2100 * 2 = 42003 months, profit is 4200 * (1 + 25%) = 5250
What does multiplication mean in solving practical problems by proportion in primary school mathematics
Generally speaking, the multiplication in solving practical problems by proportion in primary school mathematics means that the product of two quantities is certain, but it means that the product of two quantities in inverse proportion is constant
For example, if you burn 2 tons of coal a day, you can burn 180 days. If you burn 3 tons a day, how many days can you burn?
At this point: tons burned per day x days burned = total tons of coal (unchanged)
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