Update 1: diagram of question 4.

Update 2: Head and tail of fitness trail

Update 3: 3. A street lamp is installed every 15m on both sides of the 7500m fitness trail.

Street lamps are needed for fitness trails, heads and tails.

How many lights should be installed in the whole fitness trail?

(1) Let 7A4B be divisible by 55.

That is, it can be divisible by 5 and 1 1. B can be 0 or 5; (7+4)-(A+B) must be a multiple of 1 1 = >; 1 1-(A+B) is a multiple of 1 1 = & gtA+B is a multiple of 1 1. If B=0,

Then A=0 and the number is 7040. If B=5,

Then A=6, the number is 7645 (2) (a+b+c+d)/4 = 38 = >; A+B+C+D = 38 * 4 = 152(A+B)/2 = 60 = & gt； A+B= 120 Therefore, the average value of C+D = 152- 120 = 32 C and D = (C+D)/2 =16 (3) Street lamps beside the fitness path =

That is, the whole square area >; 15.75

So if the side length of a square is 4 meters, it will be larger, and if the side length of a square is 4 meters.

That is, the remaining rectangle is 3 meters.

Area = 3 * 4 =12m2; If the side length of a square is 5 meters,

That is, the remaining rectangle = 4m.

Area =4*5 = 20 square meters, if the square side length = 4.5 meters.

That is, the remaining rectangle = 3.5m.

Area = 3.5 * 4.5 =15.75m2 = 4.5 *1= 4.5m2. Middle school solution: Let the side length be x meters x (x–1) =15.75x2–x–65438+.

1. Maybe 7040.

7645 2.(38x4)-(60x2) and points; 2 3.(7500 & points; 15+ 1)x2 plus 1, because the meter is 4. 4.5 square meters.

1) wer is 7040, because 5 or 0 can only be divided by 5; 2) A+B+C+D = 4x38 .............. (1) A+B = 2x60 ............................... (2) (1)-(2) We have.

C+D = 152 - 120

Therefore, C+D = 32, and the average value of c and d is equal to 32/2 =16; 3) 7500/15 = 500. Therefore, since street lamps should be installed at the starting point and end at the end point, there will be 500+1= 501; 4) This is a rather quadratic problem. Let y be the unknown length (m) of a rectangle, and its width is1m15.75 = y (y-1) (square meter). Therefore, the square is equal to Y x Y (square meter).

Y 2-y-15.75 = 0 to solve the quadratic equation, we have Y = 4.5 or Y = -3.5 (rejection is no negative result). therefore

The area of a rectangle is equal to 4.5x 1 = 4.5 (square meter) 2010/-19 23: 26: 37 Supplement: Question (2). Is 50 1 x 2 = 1002 street lamps, because the problem requires installation on both sides of the road.

1.7040 2.38 x2-60 = 16 3.7500/ 15+ 1 = 50 1

1. A four-digit 7 []4 [] can be divisible by 55.

Find out the possible four digits. Answer 7040 Other 5 knowledge

Reference: self