Which statements must be true to model a data set using a normal distribution? The sample mean must equal the population mean.
The standard deviation of the population must be less than 30.
The sample must be randomly selected.
The sample size, n, must be at least 30.
The population mean must be greater than the sample mean.

If the ratio of sum of the first m and n terms of an ap is m2 : n2 , show that the ratio of its mth and nth terms is (2m − 1) : (2n − 1).

The function f(x)= x5+ ( x + 3)2 is used to create a table. if x = -1 then what is f(x)?

Bill makes leather shoes. he charges $45 for a pair of women's shoes and $50 for a pair of men's shoes. he sells x pairs of women's shoes and y pairs of men's shoes each week and earns a total income of $2,500. this situation can be represented by the equation . if bill has no female customers during a particular week, he needs to sell pairs of men's shoes to earn his weekly income of $2,500.