2. Một kỹ sư nông nghiệp muốn ước lượng tỉ lệ nảy mầm của một loại hạt giống. Người kỹ sư đó đem gieo thử 1000 hạt giống thì thấy có 640 hạt nảy mầm.
a) Hãy ước lượng khoảng tin cậy 90% cho tỉ lệ những hạt nảy mầm.
b) Nếu muốn có độ tin cậy 90% và bán kính ước lượng không vượt quá 0,02 thì cần lấy mẫu có kích thước bé nhất là bao
nhiêu?

Find the area of an equilateral triangle with a side of 6 inches

Circle a has a diameter of 7 inches, a circumference of 21.98 inches, and an area of 38.465 square inches. the diameter of circle b is 6 inches, the circumference is 18.84 inches, and the area is 28.26 square inches. part a: using the formula for circumference, solve for the value of pi for each circle. (4 points) part b: use the formula for area and solve for the value of pi for each circle. (4 points)

Students at a high school were asked about their favorite outdoor activity. the results are shown in the two-way frequency table below. fishing camping canoeing skiing total boys 36 44 13 25 118 girls 34 37 22 20 113 total 70 81 35 45 231 select all the statements that are true based on the given table. more girls chose camping as their favorite outdoor activity than boys. more girls chose canoeing as their favorite outdoor activity than those who chose skiing. more boys chose skiing as their favorite outdoor activity than girls. there were more boys surveyed than girls. twice as many students chose canoeing as their favorite outdoor activity than those who chose fishing. more students chose camping as their favorite outdoor activity than the combined number of students who chose canoeing or skiing.