Suppose that when A is half the age of B, A is one year old, B 2×A is old, and C 38 is old; When A is 17 years old, it is noted that the age difference between A and B is unchanged, so B is 17+a, so C is twice that of B, which is 2×( 17+a). According to the age difference between A and C, we can get: 38-A = 2× (65438+A). B is 14 years old, C is 38 years old, and the total is 7+ 14+38=59 years old, (113-59) ÷ 3 =18. In 18 years, the sum of their ages will be 60.
2. A workshop needs to process a batch of parts. If it is necessary to process 28 parts per hour, it can be finished 10 hour in advance. If 20 parts are processed per hour, it can be finished 6 hours in advance. How many parts are there in this batch?
(28× 10-20×6)÷(28-20)=20
28×(20- 10)=280.
Examination Paper Unit 7 Mathematics and Physical Education Examination Paper (Volume B)
Fill in the blanks.
1. There were () days in February of the year when the Beijing Olympic Games was held.
2. Wheels with a radius of 0.3m.. When the wheel speed reaches 600 revolutions per minute, the speed of the car is kilometers per hour.
3.a and B go the same way. It is known that their speed ratio is1/9:110, so the ratio of the time required for A and B to walk is ().
The highway from Nanjing to Shanghai is 280 kilometers long. A bus left Nanjing at 9: 00 am and arrived in Shanghai at 65: 438+0: 00 pm, stopping for half an hour on the way. This bus runs at an average speed of 100 km per hour.
5. It takes 16 seconds for a train to cross a 500-meter-long bridge (from the front bridge to the back bridge), and 22 seconds to cross an 800-meter-long tunnel. The speed of this train is () m/s, and the body is () m long.
6.5 Students share 3 bicycles, and everyone takes turns riding them. From 14: 00 to 15: 00, the bicycle did not rest, and each student rode a bicycle on average () points.
7. Xiaoming's watch gains two seconds in eight hours, and gains () seconds if it is not adjusted for one week.
8. The athlete's specialty is the triple jump. At ordinary times, his best result in long jump is 5 meters per step, *** 15 meters. Later, through research and observation, he found that when the first or second step reduces 1%, the third step can increase by 2%, when the second step reduces by 2%, the third step can increase by 4% ... but when the current two steps reduce by more than 5%, the distance of the third step will decrease. If the first or second stage increases by 1%, the third stage decreases by 2. Please design how the athlete should practice the triple jump so that his best result in three steps can reach meters.
Second, answer the following questions and write the process.
1.A and B two cars leave from A and B at the same time and drive in opposite directions. It takes 4 hours for the A train to travel from A to B, and the B train travels every hour15km. When they met, a car walked three-fifths of the way. How many kilometers is it between A and B?
2. Lingyan Mountain height 1 km. It takes Mr. Chen 40 minutes to climb the mountain and only half an hour to descend it. Find the average speed of going up and down the mountain.
3. Tortoise and Rabbit Race, the whole distance is 2000 meters. The tortoise climbs 20 meters per minute and the rabbit runs 250 meters per minute. The proud rabbit slept on the road and woke up to find that the tortoise had reached the finish line, and he was still 250 meters away from the finish line. How many minutes did the rabbit sleep?
4. It takes 4 hours for a car to drive from A to B, and 6 hours for a truck to drive from B. The two cars start from A and B at the same time and meet at a distance of 24 kilometers. How many kilometers is it between A and B?
Xiaoming lives away from school1.2km. He walks to school every day. If you run 60 meters per minute, you will be 2 minutes late. If he wants to arrive three minutes before class, how many meters does he have to walk every minute?
6. Bicycle tires are scrapped when the front wheels are installed for 4000 kilometers. If installed on the rear wheel, it can only travel 3000 kilometers. Travel as far as possible. How many kilometers can a pair of tires mounted on a bicycle travel after a certain distance if the front and rear tires are interchanged? (Numbers are reserved as integers)
7. As shown on the left, the small circle is inside the big circle, and the two circles have a common point A. Two ants start from point A at the same speed and crawl on the big and small circles at the same speed according to the direction indicated by the arrow. It is known that the diameters of two circles are 32 cm and 20 cm respectively. Q: When the ants on the small circle crawl several times (back to point A), are the two ants the farthest apart?
8. After school, Xiao Qiang walked south along Renmin Road at a speed of 60 meters per minute. Every 10 minutes along the way, a 1 bus overtook him from behind, and every 8 minutes, another oncoming 1 bus was encountered. If 1 bus runs at the same speed at equal intervals, what is the departure time interval of 1 bus?
answer
I.1.29 2.67.824 3.9:10 4.80 5.50 300 6.36 7.428.15.5
2. 1.4×3/5× 15÷( 1-3/5)= 90(km)。
2.2000 ÷ (40+30) = 200/7 (m/min).
3.2000 ÷ 20-(2000-250) ÷ 250 = 93 (points).
4.24÷[ 1/2- 1÷( 1/4+ 1/6)× 1/6]= 240(km)。
5. 1200÷( 1200÷60-2-3)= 80m/min。
6.2 (1/4000+1/3000) ≈ 3429 (km).
7. The least common multiple of16 and 20 is 80, the small circle has 4 turns, and the big circle 2 has 1/2 turns.
8. Let 1 bus speed be x m/min,10x-60x10 = 8x+60x8x = 540.
The distance between two buses in the same direction 1 is: 540×10-60×10 = 4800 (meters).
4800÷540= 8 8/9 (points)
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