A cross-country runner runs 10km in 40 minutes. What is his average speed
2007-02-24 09:56:48 · 6 answers · asked by Nikki 1 in Science & Mathematics ➔ Mathematics
rate X time = Distance
r X 40 mins = 10km
r = 1km/4min
2007-02-24 10:00:56 · answer #1 · answered by Jason 3 · 0⤊ 0⤋
ok. im gonna try and make this as easy as i can. im not gonna use formulas or anything. so anyway.
1. make it into a fractioin. 10km/40min
2. reduce by dividing by 10. 1km/4min
3. if you want to find the average speed in an hour it would be easiest to make it a certain amount of km in 1minute, not 4. so 4 divided by what is 1? yep. 4. so you have to divide 1 by 4. just in case youre not to good with decimals thats .25km. .25km/1min
4. so in 1 minute she goes .25km.
extra:
5. if youre trying to find the average in hours you have to do something else. take the number you got in #4. now 1 minute times what is 60mins? yep. 60. so you have to multiply .25km by 60. that is 15.
so she can run 15km in 1hour and .25km in 1minute.
2007-02-24 23:15:54 · answer #2 · answered by Hannah A 1 · 0⤊ 0⤋
10 km in 40 minutes = 1/4 km in one minute average
If per hour is requested, 5 km in 20 minute, so 15 km per hour.
2007-02-24 18:03:21 · answer #3 · answered by BILL@CA 5 · 0⤊ 0⤋
ok
10/40 = X/ 60 where 60 is minutes per hour
40X= 600
X= 600/40
X=15 km per hour average speed
2007-02-24 18:01:29 · answer #4 · answered by k k 72 2 · 0⤊ 0⤋
d = rt
10 = r(40)
r = 1/4 km/min or
r = 15 km/hr
2007-02-24 17:59:44 · answer #5 · answered by richardwptljc 6 · 0⤊ 0⤋
average speed = distance/time
= 10km/40min
=1/4 km/min or .25 km/min
If you want km/hr, then multiply:
.25 km/min x (60min/1hr) = 15 km/hr
2007-02-24 18:01:28 · answer #6 · answered by andthendougsaid 2 · 0⤊ 0⤋