Welcome Assignment 4 - Math Problems (14 questions 28 points ) Show all work and units. METRIC CONVERSIONS ips-for-ap-exam.pdf for details. PERCENTAGES ' f for details. 7) Calculate the percentage growth rate for a country with a population of 7 million in a year in which it had 100,000 births, 70,000 deaths, 30,000 immigrants, and 40,000 emigrants. 8) If the concentration of mercury in a water supply changes from 55 ppm to 8 ppm in a ten year period, what is the percent change of mercury concentration? What 1s the percent change per year? 9) If 25% of a natural area is to be developed, leaving 500 acres untouched, how many acres will be developed? 10) A natural gas power plant operates at 60% efficiency. If one cubic meter of natural gas provides 1000 BTU of electricity, how many BTU of waste heat is produced? DIMENSIONAL ANALYSIS / UNIT CONVERSIONS / FACTOR LABEL Use the following conversion factors for the problems below. 1 mi* = 640 acre (ac) 1 ac = 0.405 hectares (ha) 1 barrel oil = 42 gallons (gal) 1 L=0.264 gal 1 kilowatt-hour (kWh) = 3.4 x 10* British Thermal Units (BTU) = 8.6 x 10 calories (cal) 11) A 200-square mile area of a forest occupies how many acres, in both standard and scientific notation? 12) A 200-square mile area of a forest occupies how many hectares, in both standard and scientific notation? 13) How many kWh does a city consume monthly, if it uses 70 billion BTUs of energy each month? 14) One barrel of crude oil produces six million BTU of energy. How many BTU will one liter of crude oil provide, in both standard and scientific notation? How many calories of energy will one gallon of crude oil provide, in both standard and scientific notation