Question 1.
A quantity of bacteria is placed in a Petri dish at 8:00am. The bacteria doubles once every 5 minutes. At 10:00am the dish is full. At what time did the bacteria fill half of the dish? (Answer in format HH:MMam with no leading zero)

Question 2.
An unusual water lily doubles in size every day. A specimen is discovered on a lake and it is estimated that it will cover the entire lake in 30 days time. After 20 days (i.e. 10 days before the lake will be fully covered), what will be the ratio of the total area of the lake to the area already covered?
:1

Question 3.
If a long enough sheet of paper 0.1mm thick could be folded in half 29 times, what would be the resulting thickness to the nearest mm?
mm

Question 4.
The population of a country is 90 million people and growing at a steady rate of 1 percent per annum. If population growth were to continue at 1 percent, how many extra people (rounded to the nearest million) will have been added to the population in 50 years time?
million

Question 5.
The population of a country is 280 million people and growing at a steady rate of 1 percent per annum. If population growth were to continue at 1 percent, what would be the total population (to the nearest million) in 400 years time?
million

Question 6.
Dr Fred Bloggs contends that all humans can be traced back to 20 individuals living 100000 years ago. Present world population is 6.6 billion. If Dr Bloggs is correct, what would be the average population growth rate (in percent) over that time? (Answer should be rounded to 3 decimal places.)
percent

Question 7.
If the number of registered vehicles is growing at a steady exponential rate of 2.2 percent: rounded to the nearest year, in how many years will the number of vehicles double?
years

Question 8.
The number of houses in a city is growing at a steady exponential rate. Over the last 77 years the number of houses has doubled. In how many years from now will the number of houses be 4 times what it is now?
years

Question 9.
The consumption of widgets began from a small value in 1708 and has always been growing at a steady exponential rate. Today the rate of consumption of widgets is double what it was in 1972. Between 1708 and 1972 the amount of widgets consumed was 108265 tonnes. How many tonnes of widgets were consumed between 1972 and today?
tonnes

Question 10.
An unusual lily doubles in size every day. A specimen is discovered on a lake and it is estimated that the lake is 40000 times the size of the lily. Rounded to the nearest day, how many days will it be before the lily covers the entire lake?
days

Question 11.
Every few decades the rate of global energy consumption doubles. Dr Joe Bloggs estimates that the available solar energy on earth is 5000 times the amount of energy consumed globally. If Dr Bloggs is right, rounded to the nearest whole number how many times can global energy consumption double before it exceeds the amount of solar energy available?
times

Question 12.
The total amount of a renewable energy resource available to a particular country is 12000 times present annual energy requirements. Energy demand is growing at a steady rate of 2 percent per annum. If demand continued to grow at this rate, in how many years (rounded to the nearest year) would demand exceed the resource available?
years

Question 13.
Professor Fred Nirk estimates global recoverable coal reserves as being 260 times the present annual rate of consumption. According to the Bloggs Insitute, the annual rate of growth of coal consumption is 2 percent and will continue to grow at that rate for the indefinite future. If Professor Nirk and the Bloggs Institute are both correct, how long (rounded to the nearest year) will the resource last?
years

Question 14.
If global recoverable coal reserves were 100 times the present annual rate of consumption and consumption grew continuously at 2 percent per annum, reserves would last 55 years. XYZ Coal Inc. agrees with the Bloggs Institute forecast of future consumption growth of 2 percent but believes recoverable coal reserves are not 100 times but 700 times present annual consumption. If XYZ Coal Inc. is correct, how many years (rounded to the nearest year) will the resource last?
years

Question 15.
Professor Newcomb believes that if the entire world was converted to nuclear fission power the world could sustain an energy consumption growth rate of 1.0 percent for at least the next 1000 years.
If Professor Newcomb is right, as a multiple of present annual consumption, what total resource of nuclear fuel (rounded to the nearest whole number) would be required for the next 1000 years at that growth rate?
times