Logarithm Problems

A bacteria culture starts with 1000 bacteria and doubles in size every hour. How many bacteria will be present after 6 hours?

• 5000

• 64000

• 128000

• 32000

If a car depreciates by 10% each year, how many years will it take for the car's value to decrease by 50%?

• 10 years

• 3 years

• 7 years

• 5 years

A sound is 120 decibels at its source. If the intensity of sound decreases by 6 decibels for every doubling of distance, how far away is the listener if the sound is 60 decibels?

• 2048

• 512

• 1024

• 4096

If a population of rabbits doubles every month and starts with 100 rabbits, how many months will it take for the population to reach 1600 rabbits?

• 4

• 3

• 6

• 5

The pH of a solution is 3. If the pH scale is logarithmic and each whole number change represents a 10-fold change in acidity, what is the hydrogen ion concentration of the solution?

• 0.1 mol/L

• 0.01 mol/L

• 0.001 mol/L

• 1 mol/L

If an investment grows by 5% annually, how many years will it take for the investment to double in value?

• 20 years

• 15 years

• 10 years

• 25 years

The Richter scale measures the intensity of earthquakes. If an earthquake measures 6 on the Richter scale and each whole number increase represents 10 times more ground motion, how many times stronger is a 7 on the Richter scale compared to a 6?

• 15 times

• 20 times

• 10 times

• 5 times

If a radioactive substance decays by half every 10 years, how many years will it take for 90% of the substance to decay?

• 40 years

• 50 years

• 30 years

• 20 years

The temperature of a cup of coffee decreases by 10 degrees Celsius every hour. If the initial temperature is 80 degrees Celsius, what will be the temperature after 3 hours?

• 60 degrees Celsius

• 40 degrees Celsius

• 70 degrees Celsius

• 50 degrees Celsius

If a computer virus infects 1000 computers and spreads to double the number of computers every hour, how many hours will it take for 1 million computers to be infected?

• 12

• 8

• 15

• 10