Cho một chùm chìa khoá có 5 chìa trong đó có 2 chìa mở được người ta thử ngẫu nhiên từng chìa cho đến khi mở được nếu không mở được thì bỏ ra. Gọi x là số lần thử hãy lập bảng phân phối xác suất của x

Jeffery conducted a survey in his school and found that 30 of the 50 eighth grade students' favorite subject is mathematics. based on the results, jeffery concluded that out of the 200 students in his school, 120 students' favorite subject is mathematics. select the statement that is true about jeffery's conclusion. a. jeffery's conclusion is not valid because the sample was biased since only 200 students were surveyed. b. jeffery's conclusion is valid because the sample was random since all of the students were eighth grade students. c. jeffery's conclusion is valid because the sample was random. d. jeffery's conclusion is not valid because the sample was biased since all of the students were eighth grade students.

The sixth grade art students are making a mosaic using tiles in the shape of right triangles.each tile has leg measures of 3 centimeters and 5 centimeters.i f there are 200 tiles in the mosaic what is the area of the mosaic.

Daniel bought a computer game for $25 and later sold it to thomas for a 40% profit. how much did daniel sell the computer game for?