A car has an average speed of 72.6 km/h for one hour, then an average speed of 94.3 km/h for two hours during a three-hour trip. What was the average speed for the three-hour trip?
2006-09-22 08:22:13 · 10 answers · asked by E 1 in Science & Mathematics ➔ Mathematics
In the first hour it covered 72.6km. In the second and third it covered 94.3*2 or 188.6km. (72.6+188.6)km/3 hours = 261.2/3 = 87.1 km/h average speed.
2006-09-22 08:26:49 · answer #1 · answered by Joe B 3 · 2⤊ 0⤋
Given:
a=72.6 ;The average speed of the car in the first hour
b=94.3 ;The average speed of the car in the second hour
c=? ; The average speed of the car in the third hour
The difference in average speeds is:
b - a = 94.3 - 72.6 = 21.7 km/h
Since there is a discrepancy in the average speeds, we can only assume that the car is still speeding up during the third hour. Assuming the rate above (b - a) increases by the hour (t), the average speed of the car on the third hour (t = 3) must be:
c = a + (t - 1)(b - a)
c = 72.6 + (3 - 1)(94.3 - 72.6)
c = 72.6 + 2(21.7)
c = 116 km/h
Verifying b given (b - a) = 21.7 and t = 2...
b = 72.6 + (2 -1)(21.7)
b = 72.6 + 21.7
b = 94.3 km/h
Verifying a given (b - a) = 21.7 and t = 1...
a = 72.6 + (1 - 1)(21.7)
a = 72.6 + 0(21.7)
a = 72.6 km/h
Therefore, the average speed of the car at the third hour is
c = 116 km/h, with assumption above.
2006-09-22 09:00:12 · answer #2 · answered by CALOi 2 · 0⤊ 0⤋
Take all 3 averages:
72.6 for hour #1, 94.3 for hour #2, and 94.3 for hour #3
add them together and divide by 3 to find the average:
(72.6+94.3+94.3)/3=
261.2/3=87.06
87.1 km/h
2006-09-22 08:28:08 · answer #3 · answered by Anonymous · 1⤊ 0⤋
total distance covered in 1st hour=72.6 km
total distance covered in last 2 hours=94.3*2 km=188.6km
total distance covered in 3 hour=261.2 km
average speed during a 3-hour trip=261.2/3=87.066666666
2006-09-22 08:40:29 · answer #4 · answered by Anonymous · 0⤊ 0⤋
72.6 km/h for one hour X1=72.6*1
94.3 km/h for two hours X2=94.3*2
Average A=X/t
A=(X1+X2)/t1+t2
A=(72.6*1+94.3*2)/(1+2)
A=87,0667 km/h
2006-09-22 08:25:20 · answer #5 · answered by runlolarun 4 · 1⤊ 0⤋
incorrect, 'marwa.' Your answer could be impressive if the vehicle had an properly-known speed of 80km/h for one hour, and then ninety for yet another hour. however the difficulty states that the vehicle had an properly-known speed of ninety km/h for 2 hours, no longer one. subsequently the properly-known speed for the entire holiday could be discovered as: (80+ninety+ninety) / 3 = 86.sixty seven km/h.
2016-10-17 11:18:02 · answer #6 · answered by ? 4 · 0⤊ 0⤋
(72.6+94.3+94.3)/3 =
I don't have a calculator close by...
2006-09-22 08:26:39 · answer #7 · answered by ///M5 1 · 0⤊ 0⤋
87.06666666666667 km/h By the way there is a calculator in windows for you M.
2006-09-22 08:34:07 · answer #8 · answered by Bill G 2 · 0⤊ 0⤋
do your own homework you simp
2006-09-22 08:32:40 · answer #9 · answered by Anonymous · 1⤊ 0⤋
87.1 kph
2006-09-22 08:27:38 · answer #10 · answered by Toy 2 · 1⤊ 0⤋