1. Here are a series of general numbers:

9、20、33、48、65、84、……

Number 4 1 Yes (2009)

2. This year marks the 60th anniversary of the founding of People's Republic of China (PRC). In the grid diagram below, the side length of each small grid is 7cm. The area occupied by "60" in the figure is (2009) square centimeters. (Figure omitted)

There are 20 seats in a row of chairs, some of which have been taken. Xiaohong looked at it later. No matter where she sat, she had to be next to the person sitting. Before Xiaohong came, at least seven people had been seated.

4. There is a rope with a length of 180 cm. Xiao Ming starts from one end and makes a mark every 3 cm. Xiaohong starts from the other end and makes a mark every 4 cm. If you cut it at the marked place, the rope will be cut into (90) pieces.

5. There are (4) different possibilities for the sum of five numbers on each great circle.

6. There are 54 cards in a deck, including four colors 13 cards and big and small kings 1 card. Get at least (15) cards, so as to ensure that there must be four cards of the same color.

7. Sketch Drawing a straight line in a 6×6 square can pass through at most (1 1) small squares.

8. Xiaohong brought 5 1 yuan to buy a pen. There are pens from 2 yuan, 3 yuan, 4 yuan and 5 yuan. Xiaohong should buy at least 2 pieces at each price. Xiaohong can buy (19) pens at most.

9. sketch

10. Put five math cards of 0, 2, 3, 5 and 8. Randomly select three sheets and put in three digits, so the possibility of putting in even numbers is (5/8).

1 1. Some students in Class One, Grade Five took part in extracurricular interest activities. 4/9 students in the class took part in music interest activities; Class 3/5 participated in art interest activities; There are 8 people who participated in both activities; There are 6 people who didn't participate in both activities; There are (45) students in this class.

12. The sketch needs at least 27 cubes.

Second, answer

1。 A total of 44 teachers and students participated in voluntary tree planting activities. Teachers plant 5 trees each and students plant 2 trees each, which is exactly 100 trees. How many teachers and students are there to plant trees?

Suppose they are all students.

2×44=88 (tree)

100-88= 12 (tree)

12÷(5-2)=4 (person)

44-4=40 (person)

There are 40 students and 4 teachers.

2 sketch:

34700 (square centimeter)

Students from several schools took part in the TV invitational tournament, and the ratio of male to female was 8:5. Later, 20 girls signed up for the competition. At this time, the number of girls accounts for 5/ 1 1. How many students are taking part now?

20(5/6-5/8)= 96 people

96÷ (1-5/11) =176 people.

There are 56 trekking teams, equipment teams and aerial echelons participating in this year's National Day military parade. Among them: the number of air echelons is 6/7 of the number of trekking teams; 1/5 of the number of equipment teams is exactly equal to 1/2 of the number of airborne echelons. How many trekking teams, equipment teams and aerial echelons participated in this year's National Day military parade?

Solution: let the number of people on foot be X.

5/2X+7/6X+X=56

X= 14

Empty: 14×6/7= 12 (pieces)

Equipment:12×1/2÷1/5 = 30 (pieces)

5。 Bear, pony, calf and deer each take a bucket and go to the faucet to receive water at the same time. They can only pick up water one by one.

It takes a bear five minutes to carry a bucket of water, a pony three minutes, a calf seven minutes and a deer two minutes.

(1) To minimize the sum of their waiting time (including water receiving time), how should they arrange their water receiving sequence?

Deer-pony-bear-calf

(2) What is the shortest total waiting time?

2+2+3+2+3+5+2+3+5+7=34 (point)

6。 Xiaoming and grandpa are walking by the lake. They started from a place by the lake at the same time and walked in the same direction. If everyone walks slowly, Xiao mingcan will catch up with grandpa after walking three times; If they all walk fast, Xiao Ming can catch up with Grandpa after six laps. It is known that both of them walk 9 meters faster than walking slowly, so how many meters does Xiaoming walk fast every minute?

Solution: Let Xiaoming's walking speed be X, then Grandpa's walking speed is 2/3X.

(X+9)(2/3X+9)=6:5

X=9

9+9 = 18m/ min