Fill in the blanks
1, 6 kg of peanut oil in a barrel, oil poured for the first time 1/3, oil poured for the second time 1/5 kg, and () 6-6* 1/3- 1/5=3.8 (.
2. Two-thirds of Class A is equal to three-quarters of Class B, and the ratio between Class A and Class B is ().
(3/4)/(2/3)=9/8, so the answer should be 9: 8.
3. The picture below is the statistical chart of the exam results of Class 2, Grade 6 in a school. Look at the picture and answer the questions.
The excellent rate of mathematics in this midterm exam is ()
The data on the map can't be seen clearly, and the answer may be inaccurate. It needs further revision. According to the temporary excellent 15 people, good 13 people, 4 people meet the standard, and 3 people need to meet the standard. Then the total number of people is 35, and the excellent rate of mathematics is 15/35=3/7.
Hualian Shopping Center held a promotion on May Day. Every 2 yuan's composition book, buy three and get one free. Xiaoming bought a composition book of 10 at a time, which was () yuan cheaper than usual.
If you buy 3, you get 1, one group is 4 copies, and the quotient of 10/4 is greater than 2, so you can only enjoy 2 copies, that is, 10 only takes 8 copies, so 2-2*8/ 10=0.4 (yuan).
5. There is a reservoir with 9 water pipes, one of which is the inlet pipe and the other 8 are the same outlet pipes. It is known that there is a certain volume of water in the reservoir, and the water inlet pipe is filling the reservoir with water at a constant speed. If all eight outlet pipes are opened, it will take three hours to drain all the water in the reservoir. If you open five outlet pipes, it will take six hours to drain all the water in the pool. If all the water in the pool is drained within 9 hours, you need to open the () outlet pipe at the same time. The form of this problem is a typical problem of cattle eating grass. Suppose that each outlet pipe discharges 1 unit of water every hour, 8*3=24 units of water in 3 hours, and 5*6=30 units of water in 6 hours, and the water intake per hour is (30-24)/(6-3)=2 units, which requires 2 units. The raw water in the pond is 24-3*2= 18 units, and it takes 9 hours 18/9=2 water outlets to drain the raw water. Therefore, * * * needs 2+2=4 water outlet pipes, which can be discharged in just 9 hours.
(5 * 6-8 * 3)/(6-3) = 2 (3 * 8-3 * 2)/9 = 22+2 = 4 (root)
6. Xiaoming is1880m away from school, one is uphill and the other is downhill. It took him 16 minutes to run to school. It is known that Xiaoming's average speed on the uphill road is 4.8 km/h, while the average speed on the downhill road is 12 km/
Xiao Ming spent () minutes on his way up the mountain.
Idea: First convert the speed into meters/minutes, which are 80 meters/minutes and 200 meters/minutes respectively.
If you run at 200 meters per minute, you should run 16 * 200 = 3200 meters in 6 minutes, which is 3200- 1880= 1320 meters more than the actual running. The extra distance divided by the speed difference is the time taken to go uphill:1320/(200-80) =11(minutes).
(16 * 200-1880)/(200-80) =11(minutes)
7 BD=BC，SABD=SADC= 1/2SABC，
AE:EC=5:2 and SADE:SADC=5: (5+2).
Sade = SABC *1/2 * 5/7 = 56 * 5/14 = 20 (square centimeter)
When the side of BC is divided into five segments, there are 1+2+3+4+5 small triangles * * on the side of BC.
If the AC side is divided into 6 segments, there are 1+2+3+4+5+6 triangles on the AC side.
Counting the whole big triangle, there is15+21+1= 37.
Either-or problem
∠A =∠B = 1/3∠C = 3∠A = 180 * 3/(3+ 1+ 1)= 65438。
A wholesale and retail stationery store stipulates that if you buy more than 300 pencils at one time (excluding 300 pencils), you can pay at the wholesale price; If you buy less than 300 pieces (including 300 pieces), you can only pay at the retail price. Xiaoming came to the store to buy pencils. If he buys 1 pencil for each sixth-grade student in the school, he can only pay at the retail price and needs 120 yuan. If you buy 60 more, you can pay at the wholesale price, and you also need 120 yuan. If the wholesale price is 6 yuan and the retail price is 5 yuan, there are () sixth-grade students in this school.
A 240, B 260, C 280, D 300.
According to the meaning of the question, "buying 6 pieces at wholesale price is the same as buying 5 pieces at retail price", it is possible to push the wholesale price of 6 pieces to the same as the retail price of 5 pieces. The total price of 60 pieces is unchanged, which means that when 60 pieces are wholesale price, the number of copies is more than the retail price (6-5) =1; Then the original five copies should have 5*60=300, and one person has 300 people. 60*5/(6-5)=300 Answer: D.
The key is to calculate parentheses first, and the operations at the same level are in order. If you multiply the last two terms first, it would be a big mistake.
The original formula = (1112)/(11/24) *1/4 = (11//.
There are many specific methods:
8* 10-( 16- 10)*8/2
[ 10+ 16-( 16- 10)*2]*8/2
( 10+ 16)*8/2-( 16- 10)*2*8/2
Each formula has a basis, and the final result is equal to 56 (square centimeter).
All possible results of 1
AC AD BC BD CC CD
Only when both dials point to C, the probability of meeting the requirements is 1/6.
The probability that the first turntable points to C is 1/3, and the probability that the second turntable points to C is 1/2. So the probability of quoting C twice is1/3 *1/2 =1/6.
The buyer of a shopping mall predicted that a shirt would sell well in the market, so he bought it with 80 thousand yuan. After coming out, it is really in short supply. The mall spent 176000 to buy the second batch of this shirt, which was twice as much as the first time, but the unit price was 4 yuan. The price of every shirt sold in the mall is 58 yuan. How much did the commercial building profit from these two transactions?
Second purchase quantity: (176000-80000*2)/4=4000 (pieces)
Two * * * purchases: 4000+4000/2=6000 (pieces)
Total profit: 6000 * 58-176000-80000 = 92000 yuan.
4. There are three ports A, B and C in turn on a straight line. Two ships, A and B, set out from ports A and B respectively at the same time, and sailed to port C at a constant speed in a straight line, and finally arrived at port C. The distance between port A and port B is 30km, the distance between port B and port C is 90km, the speed of ship A is 60km/h, and the speed of ship B is 30km/h. If the distance between the two ships does not exceed 10km, you can see that. When did the two ships meet before arriving at Port C?
The initial distance between the two ships is 30km, and they can see each other when they are 10km apart. Go straight ahead until ship A passes ship B 10Km, and you can see each other during this time.
Therefore, it is only necessary to calculate two times when A ship travels 30- 10km more than B ship and 30+ 10km at most.
(30- 10)/(60-30)=2/3 (hours) =40 (minutes)
(30+ 10)/(60-30)=4/3 (hours) =80 (minutes)
Verify that 60*4/3=80(km) is less than 90+30, indicating that it has not reached the C port, which is in line with the meaning of the question. The answer is that the two ships can see each other within 40 minutes to 80 minutes after departure.