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Distance, speed and time multiple choice question-HELP

Thomas Beckett decides to see how fast he can cycle from London to Brighton. He divides the journey up into three legs. His bicycle computer tells him that for the first leg he cycled 20 miles at an average speed of 15mph, for the second leg he cycled at an average speed of 20mph for 15 miles and for the third leg he cycled at an average speed of 10mph for 10 miles. Assuming his speed for each leg was constant, how long did the journey take him?


a) 1 hour

b) 11 hours and 40 minutes

c) 2 hours and 45 minutes

d) 3 hours and 5 minutes

e) Can’t say



I really don't understand why d is the answer, and how to do it! Any clues????
Also this one:

You are asked to construct a wooden block measuring 10 x 20 x 30 cm3. How many wooden cubes of 5cm3 in size do you require?


1200

125

240

400

6000

How is 400 correct, I got 48?????
Reply 2
Distance/Speed = time

1st leg: 20/15=1.333 hours (80 mins)

2nd leg: 15/20=0.75hours (45 mins)

3rd leg: 10/10 = 1 hour (60 mins)

80+45+60 = 185= 3hr 5 mins

If I haven't explained it very well please ask and I will try better :p:
Reply 3
Crystal Watson
Also this one:

You are asked to construct a wooden block measuring 10 x 20 x 30 cm3. How many wooden cubes of 5cm3 in size do you require?


1200

125

240

400

6000

How is 400 correct, I got 48?????


I'm not sure about this one either, I got 48 as well when I tried to work it out!
Ya, that is weird isn't it!!!!!! Thank you for tryin tho ;-)
WOW! you actually made the first question sound really easy though! WOW! Thank you, I understand it, so basically it is just finding the length of time required for each leg and adding it up!

But what was all that about it being the same speed, they are not the same???
Reply 6
Crystal Watson


But what was all that about it being the same speed, they are not the same???


[QUOTE="Watson" Crystal="Crystal"]Thomas Beckett decides to see how fast he can cycle from London to Brighton. He divides the journey up into three legs. His bicycle computer tells him that for the first leg he cycled 20 miles at an average speed of 15mph, for the second leg he cycled at an average speed of 20mph for 15 miles and for the third leg he cycled at an average speed of 10mph for 10 miles. Assuming his speed for each leg was constant, how long did the journey take him?


It says the speed for each leg was constant i.e. he stayed at a constant speed throughout each leg. So in section 1 he was constantly 15mph, in section 2 he was constantly 20mph, in section 3 he was constantly 10mph. (If that was what you were asking about :p:)
Reply 7
Crystal Watson
Also this one:

You are asked to construct a wooden block measuring 10 x 20 x 30 cm3. How many wooden cubes of 5cm3 in size do you require?


1200

125

240

400

6000

How is 400 correct, I got 48?????


I get 1200...

hint: the wooden cubes are 5 cm^3, not 5cm each side
Crystal Watson
Also this one:

You are asked to construct a wooden block measuring 10 x 20 x 30 cm3. How many wooden cubes of 5cm3 in size do you require?


1200

125

240

400

6000

How is 400 correct, I got 48?????

I don't think it is correct. The total volume is 10*20*30 = 6000cm^3, and your wooden cubes are 5cm^3, so the answer can't be anything other than the number of times 5 goes into 6000, which is 1200.

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