4 If the cost of the machine is $14000, its salvage value is $1500 and its estimated useful life is 5 yr, the straight line depreciation is 2500. What is Rate of depreciation per year = ? ( Hint: Given the estimated useful life)

Rental space has been increasing at 7.8% per year compounded annually. If a rentals space now costs $27 per square ft per month, what were the rental rates 7 years ago? Show work and explanations.

A radioactive substance has a half-life of 47 years. To two decimal places, how many years does it take for the quantity to be reduced by 25%?

3. A sum of money was invested at a constant interest rate compounded annually. After five years, the value of the investment is $1590.71. After fourteen years, the value of the investment is $2510.34. a) How much money was invested originally? b) Calculate the annual interest rate.