2. 30% of1/3m is (110) m; (4/5m) Add 1/5m, which means1m.
3, 40 to increase its 15% is (46); (1/4) A reduction of 20% is 1/5.
The fifth grade students planted 100 trees, and as a result, 25 trees did not survive. Later, 25 trees were replanted and all survived. The survival rate of fifth-grade students planting trees this time is (80 )%.
5. Dissolve 20g salt in 100g water, and the salt content of brine is about (16.7 )%.
6. From home to the library, Dad walks for 20 minutes and Beibei walks for 25 minutes. Dad is (25 )% faster than Beibei.
7. The purchase price of a commodity is 80 yuan. The merchant will raise the price by 50%, then set the price and give a 20% discount. If this commodity is sold 1 piece in this way, the merchant will make a profit of (16) yuan.
8. The surface area of a cube is 12cm2, and the surface area of two such cubes combined into a big cuboid is (22cm2).
9. A long-grain fragrant rice of 10 kg is 34.5 yuan, and a Wang Zhongwang rice of 5 kg 17.5 yuan. (1) Rice is cheap.
10, a story book ***80 pages. On the first day, I read 1/4 of the whole book, leaving (60) pages unfinished.
2. It is judged that 1 and 10 1 parts are all qualified, and the qualified rate of parts is 10 1%( ×).
2. Add the same amount of salt water to the salt water with a salt content of 5%, and the salt content of the salt water remains unchanged (√).
3. Adding "%"to the natural number A will reduce the number to1100 (√) of the original number.
4. A number is 20% more than B number, and C number is 20% less than A number, so B number is equal to C number (×).
5. There are two iron wires, A is longer than B13100m, and B is shorter than A 13/ 100m (√).
Iii. Calculate 1,1.2÷ (1-25%) =1.6.
3/4×2/7+75%×5/7 = 3/4
2.37÷4- 1.37×25% = 1/4
4%×25%+2/3×30% =0.2 1
2、x- 15%x=2.04
0.85 times =2.04
x= 12/5(2.4)
3/5×4/3- 10%x=0
0. 1x=0.8
x= 8
5x%+6x%=2.2
0. 1 1x=2.2
x= 20
(x+75%)×30=36
x+0.75= 1.2
x=0.45
4. Calculate 1. Car A has traveled 45% from A to B, and there is still 1 10 km from B. How many kilometers is there between A and B?
1 10÷( 1-45%﹚=200
2. By inspecting the parts processed in Li Shifu, it is found that for every 40 parts processed, there are two defective products. According to this qualification rate, how many parts does he have to process at least to process 2000 qualified products?
2000÷[﹙40-2﹚÷40]=2 10.5.26
Thirty-eight fifth-grade students went to the zoo. Ticket price 7.5 yuan/piece. Students with more than 40 students enjoy group tickets, with 20% discount for each ticket. Please calculate. How did they buy it reasonably? How much will it cost?
∵38×7.5 =285>40×7.5×0.8=240
You should buy 40 group tickets for 240.
There is a batch of salt in the warehouse. After 35% of the total quantity was shipped out, 240 tons were brought in. At this time, the salt in the warehouse is just 25% more than the original salt. How many tons of salt are there in the warehouse?
240÷[ 1+ 25%- ﹙ 1-35%﹚]=400
What is the minimum area of wrapping paper to wrap three dictionaries with a length of 20 cm, a width of 12 cm and a height of 6 cm?
Length 20 cm, width 12 cm and height 6×3= 18 cm.
2×﹙20× 12+20× 18+ 12× 18﹚= 1632
6. The price of ice cream is: 12 yuan1000g. 3 yuan 200 grams. 6.5 yuan 500 grams. What are the different ways to buy (1) 1 kg Wangwang Snow Cake?
Two kinds: 12 yuan1000g; 6.5 yuan 500g× 2
(2) 1.5 kg Want Want Snow Cake What are the ways to buy it?
Three kinds:: +2 yuan1000g; 6.5 yuan 500 grams; 6.5 yuan 500g× 3; 6.5 yuan 500g+3 yuan 200g× 5
(3) What is the cheapest way to buy 1.6 kg of snow cake?
12 yuan 1000g +3 yuan 200g× 3.
5. Brain-strengthening exercise 1, a sugar water with a sugar content of15% 450g. Now, after adding some water, the sugar content is 13.5%. Q: How many grams of water do you add?
450÷﹙ 13.5%÷ 15%﹚-450=50
There are 630 science and technology books and literature and art books in Wanghua Primary School, of which 20% are science and technology books. I bought a batch of science and technology books this semester. At present, science and technology books account for 30% of the total number of these two kinds of books. Please think about it. How many science and technology books did you buy this semester?
630÷[﹙ 1-30%﹚÷﹙ 1-20%﹚]-630=90