In two common species of flowers, a and b, the proportions of flowers that are blue are pa and pb , respectively. Suppose that independent random samples of 50 species-a flowers and 100 species-b flowers are selected. Let pˆa be the sample proportion of blue species-a flowers and pˆb be the sample proportion of blue species-b flowers. What is the mean of the sampling distribution of pˆa−pˆb ?.

Approximately workers each year are treated for injuries caused by lifts, jacks, or jack stands. a) 2,000 b) 5,000 c) 10,000 d) 15,000

Write a personal narrative essay that describes a significant experience that has shaped your identity. develop the narrative through pacing, dialogue, and details that engage the reader.

In the image, layer a is the topmost layer. layer c contains fossils from the precambrian era. layer b contains dinosaur fossils, and layer a contains fossils of mammals. which two statements are supported by this evidence? 1. mammals lived before the precambrian era. 2. dinosaurs and mammals existed in the precambrian era. 3. dinosaurs evolved after precambrian organisms. 4. precambrian organisms evolved after dinosaurs. 5. precambrian organisms were the first life-forms to become fossilized, according to this sample.