Q&A - P4 Math

[tianzhu]

Xiao Hu:

Hi Tianzhu,
The solution pasted was removed. Can you help give the solution one more time for this Q4?

\"4)There were 50 children in Xie Ming Ming’s party. Each boy ate 10 cookies. Each girl ate 7 cookies. All the girls ate 44 more cookies than all the boys. How many more girls than boys were there? (14)\"

TIA,
Xiaohu

Hi Xiao Hu

Good Morning.

Here's an earlier slide for a similar type of questions.

The solution to Xie question.

Assume all were girls.

50*7 ------ 350
(49*7) – 10 ------ 333

For every increase of 1 boy, the difference in the number of cookies drops by 17.

350 – 44 ------ 306
306/17 ------ 18

So, we have 18 boys and 32 girls.

Hence, there are 14 more girls than boys.

Best wishes

http://farm8.staticflickr.com/7016/6828705773_53738730b6_z.jpg\">

[Xiao Hu]

tianzhu:

Xiao Hu:

Hi Tianzhu,
The solution pasted was removed. Can you help give the solution one more time for this Q4?

\"4)There were 50 children in Xie Ming Ming’s party. Each boy ate 10 cookies. Each girl ate 7 cookies. All the girls ate 44 more cookies than all the boys. How many more girls than boys were there? (14)\"

TIA,
Xiaohu

Hi Xiao Hu

Good Morning.

Here's an earlier slide for a similar type of questions.

The solution to Xie question.

Assume all were girls.

50*7 ------ 350
(49*7) – 10 ------ 333

For every increase of 1 boy, the difference in the number of cookies drops by 17.

350 – 44 ------ 306
306/17 ------ 18

So, we have 18 boys and 32 girls.

Hence, there are 14 more girls than boys.

Best wishes

http://farm8.staticflickr.com/7016/6828705773_53738730b6_z.jpg\">

Hi Tianzhu,
Thanks so much. This solution to me is more than just supposition strategy. This has Suppostion, Listing/Tabulating and Looking for a pattern strategies all in.

Good question from you!!

Thanks,
Xiaohu

[chloecube]

Tim has 336 local and foreign stamps at first. He gave away 2/5 of the local stamps and 46 foreign stamps. He then found that he had 3/5 as many local stamps as foreign stamps left. How many foreign stamps did he have at first?

[tianzhu]

chloecube:

Tim has 336 local and foreign stamps at first. He gave away 2/5 of the local stamps and 46 foreign stamps. He then found that he had 3/5 as many local stamps as foreign stamps left. How many foreign stamps did he have at first?

Hi

You may use MD

Local
Gave ------- 2 units
Left ------ 3 units

Foreign
Gave ------ 46
Left ------ 5 units

10 units + 46 ------- 336
10 units ------ 290
1 unit ------- 29

Foreign stamps @first ------ (5*29) + 46 ------- 191

Best wishes

[chloecube]

Thks for fast reply tianzhu

[Tresille]

Hi, need your assistance.


John has a total of 20 apples and pears. If he exchanges every pear for 2 apples, she will have 28 apples. How many apples and pears does he have? Can we use model drawing to solve this qn?

[Zack7]

Tresille:

Hi, need your assistance.


John has a total of 20 apples and pears. If he exchanges every pear for 2 apples, she will have 28 apples. How many apples and pears does he have? Can we use model drawing to solve this qn?

let x be pears
let y be apples

x + y = 20
2x + y = 28

20-x = 28 -2x
x = 8 pears
y = 12 apples



it is possible to use models to solve this question
but you have to do it to scale. or have a relative scale
like 1cm to 1 unit. but it is not an efficient way to do this sort of questions.

in fact , i just need to use logic to be able to solve this question. logic is the best approach for simple cases like these.
if 1 pear becomes 2 apples, then that would mean every pear i change to apple will yield me a net of +1

so if i have 28 as a new total, where did the 8 extra came from? it would mean i have a net of +8. then, it would mean i have changed 8 pears.

if i had 38 as a new total, it would mean 38-20 = 18, which means i have changed 18 pears and so on...

[rrjan]

Can somebody kindly help me to solve this sum using the internal transfer method? Kindly show me how to draw the models. Thanks


Qn 1) Imran had 4 times as much money as Lucy. After Imran had given Lucy $210, they had an equal amount of money left. How much did each of them have at first?

[CRAZYBANANA]

Can somebody kindly help me to solve this sum using the internal transfer method? Kindly show me how to draw the models. Thanks


Qn 1) Imran had 4 times as much money as Lucy. After Imran had given Lucy $210, they had an equal amount of money left. How much did each of them have at first?

Imran = 4u
Lucy = 1u
4u - 210 = 1u + 210
3u = 210 + 210
1u = 420 / 3 = 140
Imran = 4u = 4x140 = 560
Lucy = 1u = 140

[Xiao Hu]

Zack7:

Tresille:

Hi, need your assistance.


John has a total of 20 apples and pears. If he exchanges every pear for 2 apples, she will have 28 apples. How many apples and pears does he have? Can we use model drawing to solve this qn?

let x be pears
let y be apples

x + y = 20
2x + y = 28

20-x = 28 -2x
x = 8 pears
y = 12 apples



it is possible to use models to solve this question
but you have to do it to scale. or have a relative scale
like 1cm to 1 unit. but it is not an efficient way to do this sort of questions.

in fact , i just need to use logic to be able to solve this question. logic is the best approach for simple cases like these.
if 1 pear becomes 2 apples, then that would mean every pear i change to apple will yield me a net of +1

so if i have 28 as a new total, where did the 8 extra came from? it would mean i have a net of +8. then, it would mean i have changed 8 pears.

if i had 38 as a new total, it would mean 38-20 = 18, which means i have changed 18 pears and so on...

Hi Tresille,
For P4 level and for this question, other than Guess & Check strategy/method, can use the Supposition/Supposition & Tabulating & look-for-a-pattern strategy. Please see page 48 on one of post by Tianzhu. You can search \"\"4)There were 50 children in Xie Ming Ming’s party\". Tianzhu had given quite a lot of such questions with solutions thrown in. I encourage you to take a look.

Hope it helps.
XiaoHu.