Thế nào là một ước lượng hiệu quả? Cho X1,X2,... là một mẫu ngẫu nhiên có cỡ mẫu n(n>30) từ một tổng thể với E(X)=μ và phương sai D(X)= σ^2 (x_1+x_2+x_3)/3 và tổng x là những ước lượng không lệch hay có lệch của μ
Ước lượng nào ở câu a là ước lượng hiệu quả
Xây dựng khoảng ước lượng đối xứng cho trung bình tổng thể

Which of these is a benefit of using objects in a powerpoint presentation? a. collaborators can create the external files while you create and edit the slide show. b. you can easily change the theme and design of the presentation. c. you can have older data in the source file while having up-to-date data in the presentation. d. collaborators can easily share the presentation.

An ou structure in your domain has one ou per department, and all the computer and user accounts are in their respective ous. you have configured several gpos defining computer and user policies and linked the gpos to the domain. a group of managers in the marketing department need different policies that differ from those of the rest of the marketing department users and computers, but you don't want to change the top-level ou structure. which of the following gpo processing features are you most likely to use? a, block inheritance b, gpo enforcement c, wmi filtering d, loopback processing

Write a program that displays the following menu: geometry calculator 1. calculate the area of a circle 2. calculate the area of a rectangle 3. calculate the area of a triangle 4. quit enter your choice (1-4): if the user enters 1, the program should ask for the radius of the circle and then display its area. use the following formula: area = ď€(the square of r) use 3.14159 for ď€ and the radius of the circle for r. if the user enters 2, the program should ask for the length and width of the rectangle and then display the rectangle’s area. use the following formula: area = length * width if the user enters 3, the program should ask for the length of the triangle’s base and its height, and then display its area. use the following formula: area = base * height * .5 if the user enters 4, the program should end. input validation: display an error message if the user enters a number outside the range of 1 through 4 when selecting an item from the menu. do not accept negative values for the circle’s radius, the rectangle’s length or width, or the triangle’s base or height. note: if the user enters an improper menu choice (1-4), the program prints "the valid choices are 1 through 4. run the program again and select one of those." if the user enters a negative radius, the program prints "the radius can not be less than zero." if the user enters a negative value for height or base, the program prints "only enter positive values for base and height."