An electric bill is an essential expense for young people who get their first apartment. The following is a list of Jordan’s monthly electric bills for the past 10 months. $115, $150, $144, $126, $90, $90, $95, $110, $120, $88

Round your answers to the nearest cent.

What is the mean monthly electric bill?

What is the range?

What is the variance?

What is the standard deviation?

there is only one way to arrange all the eight relative to each other because they are not distinct. we have

now there are nine places to place an (and not more than one in one place).   because we have four symbols, we need to choose four of these nine places to insert an . order does not matter because the are not distinct.

thus there are 1 · c(9,4) ways, or, if we calculate it,

thus there are 126 ways to form such "words."

(1 km=1000m, 1m=100 cm)