Suppose we want a 90% confidence interval for the average amount spent on entertainment (movies, concerts, dates, etc.) by freshman in their first semester at a large university. the interval is to have a maximum bound on the error (or simply margin of error) of $2, and the amount spent has a normal distribution with a known standard deviation $30. the number of observations required is at least

Pls if a cow has a mass of 9×10^2 kilograms, and a blue whale has a mass of 1.8×10^5 kilograms, which of these statements is true?

Quick! a survey of 57 customers was taken at a bookstore regarding the types of books purchased. the survey found that 33 customers purchased mysteries, 25 purchased science fiction, 18 purchased romance novels, 12 purchased mysteries and science fiction, 9 purchased mysteries and romance novels, 6 purchased science fiction and romance novels, and 2 purchased all three types of books. a) how many of the customers surveyed purchased only mysteries? b) how many purchased mysteries and science fiction, but not romance novels? c) how many purchased mysteries or science fiction? d) how many purchased mysteries or science fiction, but not romance novels? e) how many purchased exactly two types of books?

What is 100,000 times 1/100,000, using the standard method of multiplication? write the answer as 10 to a power.