(2) There are five elderly people in the nursing home, with an average age of 8 1 year. Four of them are 84, 78, 83 and 85 years old respectively. Another old man is 75 years old.
(3) There are 40 boys in one class, which means that (the number of boys) accounts for 20% of the class. If there are 50 students in this class, there are 20 boys.
(4) 65,438+0) 40m in 5 of 4 is exactly (65,438+06)% of 50m; 48m minus 1 equals (36) m.
(5) Xiaohua's electricity consumption this month is 80 kWh, which is 20% lower than last month (100 kWh).
(6) A project was originally planned to be completed in 10 day, but it was actually completed in 8 days, which shortened the working time by (20)% and improved the working efficiency by (40)%.
(7) 0.3× 25% of1+65438+2.7× 3 = (direct writing)/75% of kloc-0/.225 and the product of 5 and 4 get 36. What's this number? (Equation solving)
Let this number x
75%x+5*4=36
X= 64/3
(8) The park planted 150 trees last year, and three trees died. What is the survival rate? If 800 trees are planted and the survival rate reaches 99%, how many trees can die?
Survival rate: (150-3)/ 150 = 98%
Cannot exceed: 800-800* 99% =8 trees.
(9) A basket of fruits weighs 50 kilograms. After selling 50% of the fruits, the basket weighs 27 kilograms. How many kilograms of fruit are there?
Do binary equation
Suppose the fruit weighs x kilograms and the basket weighs y kilograms.
x+y=50 ( 1)
1/2x+y=27 (2)
Substitute (2) into (1)
De: X+27- 1/2X=50
X=46 Y=4
That is, the fruit weighs 46 kilograms.
10) A road maintenance team repairs a road, and it needs to repair 10% of the total length every day. After three days of repair, it is now 960 meters. How long is this road?
3200