If Gina leaves now and drives at 66 km/h, she will reach Alton just in time for her appointment. On the other hand, if she has lunch first and leaves in 40 minutes, she will have to drive at 90 km/h to make her appointment. How far away is Alton?
Also please try to explain on how to do it cause I have a test tomorrow :(
2006-11-15 14:32:34 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
Let the time of the appointment be t in hours, with now being time zero. Then in the first case, she travels a distance of 66t kilometers. In the second case, she travels 90(t - 2/3) kilometers, because 40 minutes is 2/3 hours. Just solve the algebraic equations 66t = 90(t - 2/3) for t, and then evaluate either of the distance expressions.
2006-11-15 14:36:05 · answer #1 · answered by DavidK93 7 · 0⤊ 0⤋
Let d be the disance to Alton. In her first trip she travels d = 66*∆t, where ∆t is the time it take her on that trip. On the second trip she covers the same distance, but the time is ∆t - (40/60) (she leaves 40 minutes later, or 40/60 hr later). She covers the same distance at 90kph, so d = (∆t-2/3)*90. The distances are the same, so equate these two formulas:
66*∆t= 90*(∆t - 2/3) and solve for ∆t: ∆t*(66-90) = -(2/3)*90, or
∆t = 60/24 hr. The distance d is then 66*∆t (see the first equation) or 165km
2006-11-15 14:49:18 · answer #2 · answered by gp4rts 7 · 0⤊ 0⤋
fisrt of all,you should come to know that,no matter what manner Gina takes to complete this journey,the distance is always the same,Suppose it takes Gina X hours to reach her destination at the speed of 66km/h.then we can get the following equation
66X=90(X-40/60) X=2.5 so the distance is 66*2.5=165km
2006-11-15 14:45:22 · answer #3 · answered by peterwan1982 2 · 0⤊ 0⤋
I'm no math pro, and I know its not necessarily a difficult question, so bare with me....
distance = rate * time
therefore
distance = 90 * 40/60 OR 90 * 2/3
then
distance =60km/h
2006-11-15 14:37:59 · answer #4 · answered by Anonymous · 0⤊ 0⤋