Maths question.

onejontwo
onejontwo Posts: 1,089 Forumite
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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.
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  • arciere
    arciere Posts: 1,354 Forumite
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    He travels 35km/1.167h, that makes it 29.99km/h
  • onejontwo
    onejontwo Posts: 1,089 Forumite
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    arciere wrote: »
    He travels 35km/1.167h, that makes it 29.99km/h

    Please explain.
  • arciere
    arciere Posts: 1,354 Forumite
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    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
    onejontwo Posts: 1,089 Forumite
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    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
    stragglebod Posts: 1,324 Forumite
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    edited 14 September 2018 at 10:47PM
    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
    John_Gray Posts: 5,821 Forumite
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    How about saying that 1 hr 10 mins is 70 mins,
    speed = distance / time = 35 /70 = 0.5 km/min = 30 km/hr?
  • silvercar
    silvercar Posts: 46,945 Ambassador
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    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.
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  • jackieblack
    jackieblack Posts: 10,316 Forumite
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    edited 14 September 2018 at 6:57PM
    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 :)
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  • Chino
    Chino Posts: 2,029 Forumite
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    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
    arciere Posts: 1,354 Forumite
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    stragglebod wrote: »
    She travels 30km.
    Apologies, Italian here.
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