Nachelle just started a running plan where she runs 8 miles the first week and then increases the number of miles she runs by 5% each week. If she keeps up this plan for 18 weeks, how many total miles would Nachelle have run, to the nearest whole number?Answer:
Q. Nachelle just started a running plan where she runs 8 miles the first week and then increases the number of miles she runs by 5% each week. If she keeps up this plan for 18 weeks, how many total miles would Nachelle have run, to the nearest whole number?Answer:
Identify: Identify the initial amount of miles and the rate of increase.Nachelle starts with 8 miles and increases her running distance by 5% each week.Initial miles (a)=8Rate of increase (r)=5% or 0.05
Determine formula: Determine the formula for the total distance run after n weeks.The total distance run is the sum of a geometric series where each term is 5% greater than the previous term.The formula for the sum of the first n terms of a geometric series is Sn=(1−r)a(1−rn), where r is not equal to 1.In this case, r=1.05 (since it's a 5% increase, or 1+0.05).
Calculate total distance: Calculate the total distance run after 18 weeks.Substitute the values into the formula:S18=8(1−1.0518)/(1−1.05)
Evaluate formula: Evaluate the formula.First, calculate 1.0518:1.0518≈2.39656
Continue evaluating: Continue evaluating the formula.Now, substitute 2.39656 into the formula:S18=8(1−2.39656)/(1−1.05)
Simplify expression: Simplify the expression.Calculate the numerator:8(1−2.39656)=8(−1.39656)≈−11.17248
Calculate denominator: Calculate the denominator: 1−1.05=−0.05
Divide to find S18: Divide the numerator by the denominator to find S18. S18=−11.17248/−0.05≈223.4496
Round total distance: Round the total distance to the nearest whole number. S18≈223 miles
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