Q&A - P4 Math

[Oldschool]

fohope:

Hi,

Thanks Old school.
I have some more questions. I do not have the answer and just the questions.
Pls help me to solve. Thanks in advance.

1)There are 480 balls in a shop. 1/3 of them are footballs, 115 are basketballs and the rest are volleyballs. If 41 volleyballs and 3/4 of the footbalss are sold, how many balls will be left?

Football --> 1/3 x 480 --> 160

3/4 sold --> 3/4 x 160 --> 120 sold

No. of balls left = 480 - 120 - 41 = 319


2) Jack had 50 marbles. His sister, Jill, had 160 marbles more than him. After receiving an equal amount of marbles from their mother, Jack has 1/3 as many as Jill.
How many marbles did their mother give each of them?


Jack --> 50
Jil --> 50 + 160 --> 210

Guess and check,
1/3 --> 8/24 --> 80/240 --> 50+30 / 210+30

Mother gave each of them 30 marbles.

Alternative,

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3) There are altogether 122 cars in Car Park X and Car Park Y.Car Park Y and Cark Z have a total of 146 cars.The number of cars in Car park X is 5/8 the number of cars in Car Park Z.How many cars are there in the 3 car parks altogether?

The statement \"number of cars in Car park X is 5/8 the number of cars in Car Park Z\" means the ratio of car in X to Z is 5:8.

X : Z
5U : 8U

X + Y = 122
Y + Z = 146

Z-X = 24
8U - 5U = 24
3U = 24
U = 8

X = 5U = 40
Z = 8U = 64
Y = 122 -40 = 82

Total = X+Y+Z = 186


4)Ali had 3/5 as many green marbles as blue marbles at first . After buying another 30 green marbles , he now has 5/7 as many green marbles as blue marbles . How many green and blue marbles did he have at first?

LCM of 5 and 7 is 35, then

http://i41.tinypic.com/2gspv6b.jpg\">

[dazzlego]

Another alternative for Q2


2) Jack had 50 marbles. His sister, Jill, had 160 marbles more than him. After receiving an equal amount of marbles from their mother, Jack has 1/3 as many as Jill.
How many marbles did their mother give each of them?

The difference remained unchanged since both of them received the same amount.
In the end, Jack had 1 unit and Jill had 3 units
2 units = 160
1 unit = 80 (Jack in the end)
So, their mother gave 80 - 50 = 30

:celebrate:

[fohope]

Hi Oldschool,


Sorry, my daughter had keyed short of a phrase in question 4.
4)Ali had 3/5 as many green marbles as blue marbles at first . After buying another 30 green marbles and 30 blue marbles , he now has 5/7 as many green marbles as blue marbles . How many green and blue marbles did he have at first?
Thanks in advance.

[Oldschool]

fohope:

Hi Oldschool,


Sorry, my daughter had keyed short of a phrase in question 4.
4)Ali had 3/5 as many green marbles as blue marbles at first . After buying another 30 green marbles and 30 blue marbles , he now has 5/7 as many green marbles as blue marbles . How many green and blue marbles did he have at first?
Thanks in advance.

Hi,

No problem.

There are a number of way to solve this.

Same, using LCM of 5 and 7.
But this time, divided the added 30 blue marbles into 7 equal part.
However, has to deal with fraction in calculation.

http://i43.tinypic.com/34rgeoy.jpg\">

You can also read on the following article on another method,
http://www.kiasuparents.com/kiasu/content/math-questions-involving-changed-quantities



Regards

[tianzhu]

fohope:

4)Ali had 3/5 as many green marbles as blue marbles at first . After buying another 30 green marbles and 30 blue marbles , he now has 5/7 as many green marbles as blue marbles . How many green and blue marbles did he have at first?
Thanks in advance.

Hi

You may also consider the approach of using the \"Constant Difference Concept\" as Ali bought the same number of green and blue marbles.Hence, the difference in the number of green and blue marbles stays the same before and after.

For P4 students, a neat way is to use MD.

Hope this helps.

Best wishes

http://farm9.staticflickr.com/8123/8692429036_96cbb1557f_z.jpg\">

[fohope]

Thank you, Tianzhu.

[SAHM Chew]

Mr George raises pigs and chickens on his farm. The total number of legs of pigs and chickens is 1126. The number of pigs is 488 less than the number of chickens. How many chickens are there on his farm?


Please help to solve. Thanks.

[PapayaDad]

Assume 1 pig and 489 chicken

Pig legs = 4
Chicken legs = 489 x 2 = 978
Total legs = 982 ; not correct need 1126 - 982 = 144 more legs

If we add 1 pig, we need to and 1 chicken (to maintain "pigs is 488 less than the number of chickens") ; net result is 6 legs being added

144/6 = 24

So we need to add 24 pigs into out initial assumption ie. there are 25 pigs
so chicken is 25 + 488 = 513

Check
25 pigs = 100 legs
513 chicken = 1026
total is 1126…correct

[SAHM Chew]

Always21:

Please help me with this question



A gardener had 1/2 a bag of soil. He used 5/8 of it to fill up a pot. What fraction of the soil was left?

Thank you in advance.

Is the ans 3/16?

[The Right Equation]

SAHM Chew:

Always21:

Please help me with this question



A gardener had 1/2 a bag of soil. He used 5/8 of it to fill up a pot. What fraction of the soil was left?

Thank you in advance.

Is the ans 3/16?

yes it is.