Rosie went on a hiking trip. The first day she walked 18 kilometers. Each day since, she walked 90% of what she walked the day before.What is the total distance Rosie has traveled by the end of the 10th day?Round your final answer to the nearest kilometer.km
Q. Rosie went on a hiking trip. The first day she walked 18 kilometers. Each day since, she walked 90% of what she walked the day before.What is the total distance Rosie has traveled by the end of the 10th day?Round your final answer to the nearest kilometer.km
Identify initial distance and decrease rate: Identify the initial distance walked and the daily decrease rate.Rosie walked 18 kilometers on the first day. Each subsequent day, she walked 90% of the distance she walked the day before. This means there is a daily decrease rate of 10% (100%−90%).
Calculate distance on second day: Calculate the distance walked on the second day.To find the distance walked on the second day, multiply the first day's distance by 90%.Distance on second day = 18km×90%=18km×0.9=16.2km
Recognize pattern of distance walked: Recognize the pattern of distance walked each day.The distance walked each day forms a geometric sequence where the first term is 18km and the common ratio is 0.9 (90% of the previous day).
Use formula for sum of geometric sequence: Use the formula for the sum of the first n terms of a geometric sequence to calculate the total distance.The sum of the first n terms of a geometric sequence is given by Sn=a⋅(1−rn)/(1−r), where a is the first term, r is the common ratio, and n is the number of terms.
Calculate total distance on 10th day: Calculate the total distance walked by the end of the 10th day.Using the formula from Step 4, with a=18 km, r=0.9, and n=10:S10=18×(1−0.910)/(1−0.9)
Perform calculations: Perform the calculations.S10=18×(1−0.910)/(1−0.9)S10=18×(1−(0.910))/0.1First, calculate 0.910:0.910≈0.3487Now, substitute this value into the formula:S10=18×(1−0.3487)/0.1S10=18×0.6513/0.1S10=11.7234/0.1S10=117.234
Round final answer: Round the final answer to the nearest kilometer.S10≈117 kilometers
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