OK. A bus leaves a town at 11:45 a.m. going 30 MPH. Another bus leaves the same town on the same road at noon going at 45 MPH. When do they meet? I know how to get the answer using a graph, but she says the have to use equations. Can anyone help me? Please show your work.
Thanks,
Devon
2006-10-03 11:41:52 · 7 answers · asked by Anonymous in Education & Reference ➔ Homework Help
distance = speed x time
distance 1=30 x (1/4 + t)
distance 2 =45 t
When they meet, the distances are the same, so
30 (1/4 +t) = 45 t
7.5 + 30t = 45t
7.5 = 15 t
7.5/15 = t
.5 = t
where t is the time elapsed since the second bus left, in hours.
They meet at 12:30.
2006-10-03 11:54:42 · answer #1 · answered by Goddess of Grammar 7 · 1⤊ 0⤋
They all gave you the answer. If you can graph it then you should have been able to find the formula. See it this way:
One leaves at 11:45
One leaves at 12:00 15 minutes later (15min = 0.25 hrs).
You can either use the formula the people above gave or go through it logically which makes it longer.
When the second train leaves, the first train is 0.25 hrs ahead therefore a certain distance ahead. So find the first train's location:
X = X_initial + V.t so you get : X = 0 + 30 (0.25) = 7.5
You then know that they will meet at the same location so the two X should be equal.
For the 11:45 train you have a new X equation: X = 7.5 + 30.t
For the 12:00 train you have X = 45.t
Set them equal : 7.5 + 30 t = 45 t which yields t = 0.5 hrs.
They meet at a distance of 22.5 (which you get by plugging in the 0.5hrs in either equation) from where they left. The time will be 12:30pm.
2006-10-03 19:14:12 · answer #2 · answered by gabyrig 3 · 1⤊ 0⤋
Remember distance = rate x time. The distances will be the same when the busses meet, but the time for the second bus will be 1/4 hour less than the first. Use t for the first time, and t - 0.25 for the second. So, 30t = 45(t - 0.25) Then solve for t and add to 11:45 for their meeting time.
2006-10-03 18:55:55 · answer #3 · answered by tlf 3 · 1⤊ 0⤋
i just started algebra 1 and its a pain so good luck cuz i dont know how to do it but it might be 30x equals 40p as a variable expression good luck
2006-10-03 18:45:51 · answer #4 · answered by dfgsg 2 · 0⤊ 1⤋
collin.rasmussen@yahoo.com
He answered a similar question and he typed he will be happy to help and posted his email address
So i guess he won't mind --
2006-10-03 18:52:11 · answer #5 · answered by whadup159 3 · 0⤊ 0⤋
i hated algebra and graphing
i forgot everything
2006-10-03 18:49:16 · answer #6 · answered by veryberry 3 · 0⤊ 1⤋
Dude...do it yourself...it's not that hard...Yahoo! Answers isn't for homework help...
2006-10-03 18:50:28 · answer #7 · answered by HK3 Soul Smash 2 · 0⤊ 1⤋