If a certain pollutant decreases in concentration by 25% each year, what will be

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Question: If a certain pollutant decreases in concentration by 25% each year, what will be the concentration after 2 years if the initial concentration is 160 mg/L?

Options:

120 mg/L
90 mg/L
80 mg/L
100 mg/L

Correct Answer: 80 mg/L

Solution:

After 1 year: 160 - 0.25 * 160 = 120 mg/L. After 2 years: 120 - 0.25 * 120 = 90 mg/L.

If a certain pollutant decreases in concentration by 25% each year, what will be

Practice Questions

If a certain pollutant decreases in concentration by 25% each year, what will be the concentration after 2 years if the initial concentration is 160 mg/L?

120 mg/L
90 mg/L
80 mg/L
100 mg/L

Questions & Step-by-Step Solutions

If a certain pollutant decreases in concentration by 25% each year, what will be the concentration after 2 years if the initial concentration is 160 mg/L?

Step 1: Start with the initial concentration of the pollutant, which is 160 mg/L.
Step 2: Calculate the decrease in concentration after 1 year. This is 25% of 160 mg/L.
Step 3: To find 25% of 160 mg/L, multiply 160 by 0.25. This equals 40 mg/L.
Step 4: Subtract the decrease from the initial concentration: 160 mg/L - 40 mg/L = 120 mg/L. This is the concentration after 1 year.
Step 5: Now, use the new concentration of 120 mg/L to calculate the decrease after the second year. Again, find 25% of 120 mg/L.
Step 6: Multiply 120 by 0.25 to find the decrease, which equals 30 mg/L.
Step 7: Subtract this decrease from the concentration after 1 year: 120 mg/L - 30 mg/L = 90 mg/L. This is the concentration after 2 years.

Exponential Decay – The problem tests understanding of exponential decay, where a quantity decreases by a constant percentage over time.
Percentage Calculation – It requires the ability to calculate a percentage of a number and apply it to find the new concentration.
Sequential Calculations – The question involves performing calculations in a sequence over multiple time periods.

If a certain pollutant decreases in concentration by 25% each year, what will be

What’s inside this PDF?

If a certain pollutant decreases in concentration by 25% each year, what will be

Practice Questions

Questions & Step-by-Step Solutions

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