Ji-Hun and Kana are running a marathon. Due to the volume of people running, the starts occur in waves. Kana starts at 9:35a.m. and runs at an average rate of 7 miles per hour (mph). Ji-Hun starts at 10:00a.m. and runs at an average rate of 8mph. Assuming constant paces and no stops, to the nearest tenth of a mile, in how many miles will Ji-Hun catch up to Kana?
Q. Ji-Hun and Kana are running a marathon. Due to the volume of people running, the starts occur in waves. Kana starts at 9:35a.m. and runs at an average rate of 7 miles per hour (mph). Ji-Hun starts at 10:00a.m. and runs at an average rate of 8mph. Assuming constant paces and no stops, to the nearest tenth of a mile, in how many miles will Ji-Hun catch up to Kana?
Calculate Time Difference: Determine the time difference between Kana's and Ji-Hun's start times.Kana starts at 9:35 a.m. and Ji-Hun starts at 10:00 a.m., so the time difference is 25 minutes.Convert the time difference to hours since the speeds are given in miles per hour.25 minutes is equal to 6025 hours.
Calculate Kana's Distance: Calculate the distance Kana will have run by the time Ji-Hun starts.Using the formula Distance=Speed×Time, we calculate Kana's distance.Kana's speed is 7 mph, and the time is 6025 hours.Distance=7 mph×(6025) hours.
Set Up Catch-Up Equation: Perform the calculation from Step 2 to find the distance.Distance = 7×(6025)Distance = 7×0.4167 (rounded to four decimal places)Distance = 2.9167 miles (rounded to four decimal places)Kana will have run approximately 2.9167 miles by the time Ji-Hun starts.
Solve for Distance: Set up an equation to determine when Ji-Hun will catch up to Kana.Let x be the number of miles Ji-Hun runs until he catches up to Kana.Since Kana has a head start of 2.9167 miles, the distance Ji-Hun needs to run to catch up to Kana is x miles, and the distance Kana runs during the same time is x−2.9167 miles.Ji-Hun's speed is 8 mph, and Kana's speed is 7 mph.The time it takes for both runners to cover these distances will be the same, so we can set up the equation:Time for Ji-Hun = Time for Kana8x=7x−2.9167
Round Final Answer: Solve the equation from Step 4 to find the value of x.8x=7x−2.9167Multiply both sides by 56 (the least common multiple of 8 and 7) to clear the fractions:7x=8(x−2.9167)7x=8x−23.3336Now, subtract 8x from both sides to solve for x:7x−8x=−23.3336−x=−23.3336Multiply both sides by −1 to find the positive value of x:x=23.3336Round the value of x to the nearest tenth of a mile.x≈23.3milesJi-Hun will catch up to Kana after approximately 23.3 miles.