1. Draw the largest circle in a square with a side length of 6 cm. The circumference of a circle is (6pi)cm, and the area of a circle is (25pi)% of the square area.
2. Think about it according to the knowledge gained from the above questions. If the area is 80cm? Draw the largest circle in a square. Is the area of the circle (20pi)cm? The area of a square except the circle is (80-20pi)cm? .
3. There are ()% fewer girls than boys, and ()% more boys than girls in math interest groups.
Yesterday, in Class 1, Grade 6, two people took a day off due to illness, and the attendance rate in the morning was exactly 96%. In the afternoon, another 1 student asked for leave because of something, and the attendance rate in the afternoon was (94)%.
5. The price of a commodity is 40% profit, and the purchase price of the commodity is (60) yuan. If the sales are at least 15% off, you can earn at least (11.4) yuan for each piece sold.
6. For a barrel of oil, 20% of the barrel oil is poured out for the first time, and 25% of the remaining oil is poured out for the second time. At this time, the barrel oil is still (60)%.
7. According to Lili's statistics, the family consumption last year was: food expenditure accounted for 37% of the total expenditure, education expenditure accounted for 28% of the total expenditure, education expenditure was less than food expenditure 1.8 million yuan, and Lili's total expenditure last year was (20,000 yuan).
8. Lily cuts a circle with cardboard by hand, then draws a red line along the circle line and a yellow line along the outer line. It is known that the ring is 5cm wide and the yellow line is longer than the red line (10pi).
9. Beibei measured the circumference of a tree with a 3m-long rope and wound the rope around the trunk for 3 weeks, leaving17.4cm. The cross section of this trunk is (225pi)cm? .
10. Jiajia toffee is now 20% off. You can buy 24 kilograms before the promotion, and now you can buy (30) kilograms.
Second: judgment
1. The survival rate of planting trees will not exceed 100%. ㈤
2. Two circles with equal perimeters must have the same area. ㈤
3. For a commodity, the initial price increase is 10%, and the price decrease is 10%, and the price remains unchanged. (10)
4. The radius of the circle is increased by 10%, and the circumference is also increased by 10%. ㈤
5. Principal × interest rate ()
Three: Choice
1. Draw two circles of equal size on a piece of paper at will, and the circle formed by these two circles has at least (c) symmetry axes.
A: 0
B: 1 C:2
innumerable
2.25% fruit quality is exactly equal to 30% pear quality, so compare the quality of apples and pears (A).
A: apple weight b: pear weight c: equal d: uncertain
3. A semicircle with R has a circumference of (pi*r+2r).
A:πr B:πr+r C:(π+2)r D:2πr+r
4. Cut a piece of paper with a length of 10 cm and a width of 8 cm into the largest circle, and the circumference of this circle is (a).
a:25. 12cm B: 18.84cm C:80cm。
5. Dissolve all 25g of salt in 100g of water, and the salt content of the obtained brine is (b).
A: 25% B: 20% C: 80%
Fourth: do math.
Write directly.
2×3. 14×2.5=( 15.7)
80%÷20%=(4)
40×50%=(20)
1÷7.5%=( 13.333333)
1.2×50%=(0.6)
1.8÷9%=(200)
solve an equation
( 1- 15%)x=0.34
X=0.4
x- 13% x+5% x = 23 \ 10%
X=280.5
1.6×2+4x=30
X=6.7
30%x-20%x=x- 18
X=20
Five: the circular problem
Draw a picture and calculate.
(1) Draw a circle on the right and tell me how you found it.
(2) Draw the largest square in the circle.
(3) Is the area of a known circle 15.7cm? Find the square area you draw.
These questions are so simple that you don't have to think about them. You are so lazy that you are not qualified for the questions in the blank.