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4 problems match “distance-speed-time”. Clear

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1. Average speed over a multi-leg trip ●○○○○ 10 ptsBen drives 150 miles in 3 hours, then 120 miles in 2 hours, then 70 miles in 1 hour. Find his average speed for the entire trip in miles per hour. Round to two decimal places.
2. Average speed over equal times ●○○○○ 10 ptsShyam travels at 40 km/h for half of the total time and at 30 km/h for the other half. What is Shyam's average speed, in km/h?
3. Average speed from milestones ●●○○○ 20 ptsA car travels at a uniform speed. The driver sees a milestone showing a two-digit number $XY$. One hour later the driver sees a milestone showing the same digits in reverse order, $YX$. One hour after that the driver sees a milestone showing a three-digit number $X0Y$, with a 0 between the same two digits. What is the speed of the car, in km/h?
4. Dragon burning a village ●●●○○ 50 ptsTrodgor the dragon is burning down a village consisting of 90 cottages. At time $t=0$ an angry peasant arises from each cottage, and every 8 minutes (480 seconds) thereafter another angry peasant spontaneously generates from each non-burned cottage. It takes Trodgor 5 seconds to burn a peasant or to burn a cottage, but Trodgor cannot begin burning cottages until all the peasants around him have been burned. How many seconds does it take Trodgor to burn down the entire village?