Along with the other problems, i really need help on these 3 problems as well! i've been trying to solve them however i have no luck lol im hoping that you can help me solve them, thnx!
1) Timothy leaves home for Skedunk 400miles away. After 2 hrs, he has to reduce his speed by 20mph due to rain. if he takes 1 hour for lunch and gas, and reaches Skedunk 9 hours after he left home, what was his initial speed?
2. A highway patrolman spots a speedigcar. he clocks it at 70mph and takes after it 0.5miles behind. if the patrolman travels at an average rate of 90mph, how long before he overtakes the car?
4. A boat has a speed of 15mph in still water. it travels downstream from Greentown to Glenavon in 3/5 of an hour. it then goes back upstream from Glenavon to Cambria, which is 2 miles downstream from Greentown, in 8/5 of an hour. Find the rate of the current.
these problems have kept me stumbled! if you have any idea of how to solve them, your help will be grately appreciated =)
2007-06-14 19:36:46 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
Question 1:
It took him 9 hours in wich he didn't travel for 1 hour. So he drove for 8 hours. The first two hours he drove with speed X, the last 6 with speed Y. So the equations are:
2X+6Y = 400
Y = X - 20
Substituting the Y results in:
2X + 6(X - 20) = 400 -> 2X + 6X - 120 = 400 -> 8X = 520
So X = 520/8 = 65
So the initial speed is 65 mph.
Question 2:
The policeman has to cover 0,5 mile more. His average speed is 90 mph, 20 mph more that the other car. The time it takes to cover 0.5 mile with a speed of 20 mph is the answer so the answer is 90 seconds.
2007-06-14 20:56:20 · answer #1 · answered by EllenWhite 1 · 0⤊ 0⤋
1) Timothy leaves home for Skedunk 400miles away. After 2 hrs, he has to reduce his speed by 20mph due to rain. if he takes 1 hour for lunch and gas, and reaches Skedunk 9 hours after he left home, what was his initial speed?
Let
r = initial speed
Since he stopped for 1 hour, he travelled for 8 hours.
rate * time = distance
2r + 6(r - 20) = 400
2r + 6r - 120 = 400
8r = 520
r = 65 mph
The initial speed was 65 mph.
2007-06-15 03:47:48 · answer #2 · answered by Northstar 7 · 0⤊ 0⤋
#1 6(x-20) + 2x=400
x=35mph
2007-06-15 03:07:34 · answer #3 · answered by KJ 2 · 0⤊ 0⤋
wow
2007-06-15 02:57:09 · answer #4 · answered by Anonymous · 0⤊ 1⤋