21. When Mary and Jack bought their house, their property taxes were $3,630 annually. After 8 years, their property taxes are now $4,065.60. What percent increase is this?

Suppose that prices of a gallon of milk at various stores in one town have a mean of $3.71 with a standard deviation of $0.10. using chebyshev's theorem, what is the minimum percentage of stores that sell a gallon of milk for between $3.41 and $4.01? round your answer to one decimal place.