Maths question.

onejontwo

Probably wrong thread, but I've been racking my brains over this simple maths question:- If a person travels 35 km in 1 hour 10 mins. what is her average speed?

If you give me the answer please tell me how you arrived at the answer.

arciere

He travels 35km/1.167h, that makes it 29.99km/h

onejontwo

arciere wrote: »

He travels 35km/1.167h, that makes it 29.99km/h

Please explain.

arciere

10 minutes equal to approx 0.167 hours (1h divided by 60 times 10). Add that to the 1 hour, you get 1.167h. So the person travelled 35km/1.167h.
If you need km/h, you just divide 35 by 1.167.

Unless I got it wrong.

onejontwo

arciere wrote: »

10 minutes equal to approx 0.167 hours (1h divided by 60 times 10). Add that to the 1 hour, you get 1.167h. So the person travelled 35km/1.167h.
If you need km/h, you just divide 35 by 1.167.

Unless I got it wrong.

Is there no simpler way as this is taken from a maths paper for 10-11 year olds.

stragglebod

She travels 30km.


Lots of different ways to think about it. I'd say the easiest is to split the hour and ten minutes into 7 chunks of time, each 10 minutes long.


If it takes her 7 chunks to travel 35km then in each chunk she travels 5km. Because 35/7=5.


So if every ten minutes she travels 5km, and an hour is 6 chunks of 10 minutes, in an hour she travels 5km x 6 = 30km.

John_Gray

How about saying that 1 hr 10 mins is 70 mins,
speed = distance / time = 35 /70 = 0.5 km/min = 30 km/hr?

silvercar

Your basic equation is:

Speed = distance / time

(where / means divided by)

So to have an answer in km/h = kilometers per hour we need the distance to be in km and the time in hours.

The distance is already in km. We need to convert 1 hr 10 minutes to hours. 60 minutes in an hour. 1 hr 10 mins is 70 mins so 1 hr 10 mins is 70/60 in hours.

So your answer is speed = 35 / (70/60)

Do the 70/60 first - that equals 1.16777

Now you have 35 / 1.16777 = 29.999 rounding to 30 km/hr.

----

If you want it all as fractions and working out without a calculator:

35/ (70/60) = (35 x 60) / 70. then you would divide the 35 and 70 both by 35 to leave you with (1 x 60) /2 = 30. But I'm not sure that age group have covered the first part of that.

jackieblack

John_Gray wrote: »

How about saying that 1 hr 10 mins is 70 mins,
speed = distance / time = 35 /70 = 0.5 km/min = 30 km/hr?

This is more or less how I did it

35km/70mins = 0.5 km/min
Then x 60 = 30 km/hr

I'm pretty sure that's the way 10 year olds would be expected to work it out too

Chino

silvercar wrote: »

Do the 70/60 first

Why would you do that when you know that this will lead to a recurring decimal in the answer?

arciere

stragglebod wrote: »

She travels 30km.

Apologies, Italian here.