HELP PLEASE Which statement(s) apply to stratified random sampling? Check all that apply.
A) It can provide better estimates than a simple random sample.
B) The researcher needs some knowledge of the population in terms of characteristics relevant to the study.
C) A challenge is that it is necessary to have strata of the same size.
D) Creating strata of similar individuals to sample from reduces variability.
E) It can be difficult to obtain with a very large population.

Somone me i want to know what 18 hours out of 24 hours in a fraction

Which equation is represented by the graph below?

Suppose we have a set of small wooden blocks showing the 26 letters of the english alphabet, one letter per block. (think of scrabble tiles.) our set includes 10 copies of each letter. we place them into a bag and draw out one block at a time. (a) if we line up the letters on a rack as we draw them, how different ways coukl we fill a rack of 5 letters? (b) now suppose we just toss our chosen blocks into a pile, and whenever we draw a letter we already have, we put it back in the bag and draw again. how many different piles of 5 blocks could result? possible? piles will contain at least one repeated letter? (c) if we draw out 5 blocks wit hout looking at them, how many different piles are (d) if we draw out 5 blocks without looking at them, how many of the possible 2. (4) consider the following formula. 12 give two different proofs, one using the factorial formulas and the other combina torial.