Ước lượng không chệch là gì? Cho X_1,X_2,…,X_n là một mẫu ngẫu nhiên có kích cỡ n từ một phân phối xác suất với E(X)=μ và V(X)=σ^2. Chứng minh rằng: a) Trung bình mẫu là ước lượng không chệch của trung bình tổng thể μ.
b) Phương sai mẫu là ước lượng có chệch của phương sai tổng thể .

Use the ratio test to determine whether ∑n=14∞n+2n! converges or diverges. (a) find the ratio of successive terms. write your answer as a fully simplified fraction. for n≥14, limn→∞∣∣∣an+1an∣∣∣=limn→∞.

Which option identifies how kevin should proceed in the following scenario? four years ago kevin designed an mp3 player for young children. now that technology has changed, he would like to update his design to ensure that it encompasses cutting-edge techniques. by creating a third-angle projection of his ideas by designing an isometric projection of his new ideas by referring to past designs and illustrations of his original model by conferring with engineers who have improved upon similar devices

The length of a rectangular board is 3 feet less than twice its width. a second rectangular board is such that each of its dimensions is the reciprocal of the corresponding dimensions of the first rectangular board. if the perimeter of the second board is one-fifth the perimeter of the first, what is the perimeter of the first rectangular board?