If I increase my usual driving speed by 15 km/h, I can drive 260 km in 45 min less than usual. How fast do I usually drive?
help help help..i know this problem has something to do with rate and time [duh]..
I think you have to set up a table to solve it..
but sadly i don't know how..
PLEASE HELP!
2007-05-14 13:43:38 · 5 answers · asked by Hawthorne Heights Lover♥ 1 in Science & Mathematics ➔ Mathematics
hey you don have to use rate and speed all jus form a simple algebraic equation.
hey i already posted a picture of ur question with a worked solution at http://www.icedor.com under Elementary Maths Forum under Algebraic Manipulation. the answer i gave is labeled..
Using words to form algebraic equations
..http://www.icedor.com/icedoronline/course/index.php?cid=FLM101
2007-05-14 13:56:28 · answer #1 · answered by Anonymous · 0⤊ 0⤋
distance = speed x time
normal speed = x
Then
(x + 15)(t - 0.75) = xt = 260
So x = 260/t
put this into the first equation:
[x(t-0.75)] + 15t - 11.25 = 260
260t - 195 + 15t^2 - 11.25t = 260t
15t^2 -11.25t -195 =0
t^2 - 0.75t - 13 = 0
(t - 3/8)^2 = 13 +(9/64) = 841/64
t = 3/8 + 29/8 = 4 hours
Then Distance = 260/4 = 65 km/h
2007-05-14 13:59:34 · answer #2 · answered by looikk 4 · 0⤊ 0⤋
velocity = v
260/v - .75 = 260/(v+15)
2007-05-14 13:48:10 · answer #3 · answered by TychaBrahe 7 · 0⤊ 0⤋
have you ever heard of drt , "dirt" ? it's the type of math problem you have. you need to set up a proportion.
2007-05-14 13:52:42 · answer #4 · answered by Anonymous · 0⤊ 0⤋
sorry! I'm bad at math!
2007-05-14 13:47:08 · answer #5 · answered by ooli03 1 · 0⤊ 1⤋