Question
This question came from my reader's comment
Distance between Town X and Y is 100km.
At 07:00, Sam left Town X and cycled towards Y.
Ann left Town X and cycled towards Y at 07:30.
Ann's cycling speed was 4 km/h faster than Sam. At 10:00, Ann caught up with Samuel. When Ann was 28 km from town Y, she stopped to wait for Samuel.
(a) How far was Samuel from Ann when she stopped to wait for him?
(b) How many minutes did Ann wait for Samuel?
Answer
First answer is kind of model-based, but a bit too long. I prefer the second method which uses a triangle to represent distance/speed/time relationship. Although there is little bit of algebra, I think the kid should be able to handle it.
6 comments:
Thanks so much !! Your solutions are greatly appreciated :)
For the first answer, I didn't really get your comparison (could you explain?).
I could understand when I took
3 units of (S-4) compared with 2.5 units of S - after aligning them - I get 0.5 S = 12 --> S = 24
In the model, it represents distance which equal to speed x time.
So you are comparing (S-4)*3 and (S)*2.5
I make the model into
(S-4)*3 = (S-4)*2.5 + (S-4)*0.5
and
(S)*2.5 = (S-4)*2.5 + 4*2.5
So
(S-4)*0.5 = 4*2.5
therefore
S=24
Rooney has five more 50 cent coins than 20 cent coins. After he used eight 50 cent coins, the value of 50 cent conis is $1.50 more than the value of 20 cent coins. How many coins did he have at first?
I think it is similar to this question
Please give it a try yourself
Thank you for your help.
Amy bought an equal number of oranges and pears. The oranges were sold at 5 for $3 and the pears were sold at 4 for $5.She paid $13 more for the pears than the oranges. How much did she pay in all?
Hi there,
I'm not sure how to post a new blog, so I'm typing this as a qusetion.
Could you help me solve these 2 sums by model? I'm using algebra/units method to do so
Question 1
A flower shop had some pink and red flowers in the ratio 9:4. Thes hop sold 12 pink flowers and bought another 18 red flowers. There is now 1/2 as many pink flowers as red flowers in the shop. How many pink flowers were there in the shop at first?
[Answer = 27]
My method 2(9 units - 12) = 4 units + 18
Question 2
There were 40 more raisin buns than strawberry buns. After 3/4 of the raisin buns and 4/5 of the strawberry buns were sold, there were 28 buns left.
(a) How many strawberry buns were there at first?
(b) What fraction of the buns sold were raisin buns?
[(a)40, (b) 15/23]
Many, many thanks
Post a Comment