Final answer:
The amount of the radioactive substance left at the end of year 4 is approximately 96,041.23 grams.
Step-by-step explanation:
To find the amount of the radioactive substance left at the end of year 4, we can use the formula for exponential decay. The formula is given by:
Amount remaining = Initial amount × (1 - decay rate)number of time periods
Given that the initial amount is 150,000 grams and the decay rate is 1% per month, we need to calculate the number of time periods. Since there are 12 months in a year, the number of time periods for 4 years is 4 × 12 = 48 months. Plugging in the values into the formula, we get:
Amount remaining = 150,000 × (1 - 0.01)48 = 96,041.23 grams
Therefore, the amount of the radioactive substance left at the end of year 4 is approximately 96,041.23 grams.