mum03:

Hi Happy Holidays,


Need help on this holiday homework

Tim and Henry had an equal number of marbles each. Tim then gave away 60 of his marble while Henry bought another 33 marbles. In the end Tim had four times as many marbles as Henry. Find the number of marbles Tim had at first.

Hope someone would be able to assist.
Thks

hello, I think there's a typo? Henry should have 4 times as Tim.
Can be easily solved with a model. Need to caution the child to not be in a haste to divide the model into 4 parts, as that would make the question harder to solve.

http://i39.tinypic.com/t9zj2e.png\">

raysusan:

There were some red and blue marbles. The marbles were packed into 2 containers. At first, Container A contained 600 marbles and 40% were blue marbles. Container B contained 360 marbles and 20% of them were blue marbles. How many red and blue marbles in total must be moved from Container A to Container B such that 60% of the marbles in Container A are red and 25% of the marbles in Container B are blue?


Thank u very much.

This involves simultaneous equations to solve.


Container A has: 240 blue, 360 red
Container B has: 72 blue, 288 red

In the end, you have
60%A + 75%B = total red marbles
and
100%A + 100%B = total marbles. (because total marbles stay the same since it is an internal transfer question)

With the 2 equations,

60%A+75%B = 648 red ----------- (1)
100%A + 100%B = 960 marbles ---------(2)

Using (2) and multiply by 0.75,
75%A + 75%B = 720 ------(3)

Compare (3) with (1),
15%A = 720-648=72
100%A = 480 (This is the total marbles in Container A in the end)
60%A = 288 (this is the number of red marbles in Container A in the end)
Hence,
No. of blue marbles in Container A in the end----> 480-288=192

Remember, at first, Container A has: 240 blue, 360 red
Simple subtraction:
Blue transferred: 240-192=48
Red transferred: 360-288=72

Hope this helps.