An element with a mass of 350 grams decays by 6.6% per minute. To the nearest minute, how long will it be until there are 230 grams of the element remaining?Answer:
Q. An element with a mass of 350 grams decays by 6.6% per minute. To the nearest minute, how long will it be until there are 230 grams of the element remaining?Answer:
Determine Decay Formula: Determine the decay formula.The decay of an element can be described by an exponential decay formula, which is P(t)=P0⋅e−kt, where P0 is the initial amount, P(t) is the amount at time t, k is the decay constant, and e is the base of the natural logarithm.
Convert to Decay Constant: Convert the percentage decay rate to a decay constant.The decay rate is given as 6.6% per minute, which means that k=0.066 per minute because 6.6%=1006.6=0.066.
Set Up Equation: Set up the equation with the given values.We have P0=350 grams, P(t)=230 grams, and k=0.066. The equation becomes 230=350×e(−0.066t).
Solve for t: Solve for t.To isolate t, we first divide both sides by 350, getting 350230=e−0.066t. Then we take the natural logarithm of both sides to get ln(350230)=ln(e−0.066t)=−0.066t.
Calculate Time: Calculate the time t. We continue the calculation: t=ln(350230)/−0.066. First, calculate the natural logarithm of the ratio 350230, which is approximately ln(0.6571). Then divide by −0.066 to find t.
Perform Calculations: Perform the calculations.Using a calculator, we find ln(0.6571)≈−0.4196. Then we divide −0.4196 by −0.066 to get t≈6.3561 minutes.
Round to Nearest Minute: Round the time to the nearest minute.Since the question asks for the time to the nearest minute, we round 6.3561 to 6 minutes.
More problems from Exponential growth and decay: word problems