Natwerk Designs

how do I solve this problem?

Downtown Metropolis was a marvel of design. The streets had been laid out in a perfect grid pattern with each block measuring 500ft in length. All of the north-south roads were called streets while those that ran in east-west direction were called avenues. To keep traffic flowing as smoothly as possible, the city engineers timed it so that all of the traffic lights on the avenues changed to red at the same time. When the avenue lights turned red, the traffic lights on all of the streets turned green, in unison. on both the avenues and the streets, lights stayed green for 1 1/2 minutes,yellow for 30 seconds, and red for 2 minutes. Problem: A driver is stopped at a red light at the intersection of 5th Ave. and 6th St. He proceeds north on 6th st. to 9th Ave. where he makes a right. He then travels east for four blocks to 10th st. He takes a left on 10th st. and travels one block to his destination at the intersection of 10th st. and 10th Ave. If, between accelerating and braking, he averages 20 miles per hour between lights, what is the shortest possible time it will take him to reach the corner of 10th and 10th?

Public Comments

1. The first thing you need to do in word problems is DRAW A PICTURE. I'm not sure you can solve this problem without one. Some conversions... 1 mile = 5280 ft 20miles = 105600 ft convert 20 miles/hour to ft/minute=1760 half this is 880ft / 30 seconds A driver is proceeding north on 6th st (on a new green light) 1500 ft or 3 blocks. He makes a right hand turn and gets stopped at a red light at 9th avenue and 7th st. Since lights are red for 2 minutes, this part of the trip takes the driver 2 minutes until they can proceed. They then proceed 3 blocks which takes just under a minute and makes a left hand turn assuming they are at a light that lets you make a left hand turn without a left hand turn traffic light (here in Denver, CO we have both). So the problem becomes how long does it take the driver to travel 2000 ft added to 2min to complete the first part of their journey. distance=2000 ft at a rate of 1760 ft/min 2000ft/x = 1760/1 and solve for x 2000/1760=1.14 min add the first 2 minutes of the trip and the total trip took 3.14 minutes. If my assumption you can make a left hand turn is accurate this is the right answer. If not, then the driver will be stopped at 9st and 9th ave which will make the first part of the trip last 4 min. Then you would add how long it takes to travel 500 ft to 4 minutes. You will have to provide the interpretation of this part of this word problem based on where you live. Take care, Garth