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

Jaina and tomas are being considered as new tenants in an apartment. the landlord looks at their creditworthiness because he wants to be sure his new tenant pays the rent on time and in full. the table below summarizes the information that was on their applications. application information questions jaina tomas how many years have you had your job? 5 2 what is your monthly salary? $1,850 $2,500 how many credit cards do you have? 4 1 how much debt do you have? $13,000 $7,000 how many times were you late with payments on credit cards in the past year? 5 1 who will the landlord decide to be more creditworthy and why? tomas because the ratio of his debt to income is less. jaina because she has had her job longer, which makes her look more stable. jaina because she has more credit cards available to her. tomas because he makes more money per month.

How should you specify box sizes on a web page if you want the boxes to vary according to the font size of the text they contain? a. in pixels b. in inches c. as percentages d. in em units

Colby works as a shipping clerk for a major package delivery service. some of his daily tasks include tracking shipments and entering orders. which aspect of the information technology cluster would he most likely be trained in? a. networkingb. databasesc. hardwared. software