Q&A - PSLE Math

[qic]

Pen - 1/5

Remain - 1-1/5=4/5
Book - 1/4x4/5 = 1/5
Had left - 1-1/5-1/5 = 3/5
3 thumb Drive - 3/4x3/5 = 9/20
1 thumb Drive = 3/20
Pen - 3/20/18=1/120
number of pens - 1/5 / 1/120 = 24

Pens: 24

[pensiveowl]

qic:

Pen - 1/5

Remain - 1-1/5=4/5
Book - 1/4x4/5 = 1/5
Had left - 1-1/5-1/5 = 3/5
3 thumb Drive - 3/4x3/5 = 9/20
1 thumb Drive = 3/20
Pen - 3/20/18=1/120
number of pens - 1/5 / 1/120 = 24

Pens: 24

Thanks very much! - much simpler than the soln given in the workbook!

[anneshirleygilbert]

Can somebody please help with this question?


Samad bouoght 4 similar pens and 6 similar files. Each pen cost $1.20 more than a file. If the total cost was $6.40 more than the total cost of the pens, how much did Samad spend in all?

[tianzhu]

anneshirleygilbert:

Can somebody please help with this question?


Samad bouoght 4 similar pens and 6 similar files. Each pen cost $1.20 more than a file. If the total cost was $6.40 more than the total cost of the pens, how much did Samad spend in all?

Hi

A quick one, the answers are in odd denominations.

If the total cost was $6.40 more than the total cost of the pens ----- this means that 6 similar files cost $6.40

6F -------6.4
1F ----- 1.067

Total cost ----- 10F +4.8 -------15.47

If it's 8 files instead of 6 files, you'll get nice numbers.

Best wishes

[tisha]

atutor2001:

tisha:

[quote]
In planning for a party, Mrs Lim bought enough satay to allow her guests an average of 25 sticks each. If 2 more people joined the party, how many fewer sticks of satay will each of her guests be given?

Can no other method that can be used?
How to do tabulation, for this problem I'm not even sure where to start. :?

This is question is an example of the superiority of algebra over heuristic (but it is too complicated for Pr. However, I think GEP can still do it) Let me first present the algebraic method then the heuristic method.

Algebraic method :
Let the no. of guests be G
Let the decrease in the average be d

Before :
No. of guests = G
Average no. of satays = 25
Total no. of satay = 25G

After :
No. of guests = (G+2)
Average no. of satays = (25-d)
Total no. of satay = (G+2)(25-d) = 25G + 50 - d(G+2)

.
.
.

My above reasonings actually comes from the algebraic solution. So algebra is a mathematical tool but models and heuristics are not. We can get the heuristic concept from algebra. Good luck![/quote]:thankyou: atutor for this solution. By the time I finished reading the solution, I couldn't even recall what the Q was? :lol:
Will read again and slowly try to chew and digest. Thanks for the detailed explaination.

BTW, if the students draw some neat columns and do a few tabulations will it fetch any marks for the method :?:

[moonee]

:?: Hi can anyone help with this P5 question?


A frog took 5 leaps forward and 6 leaps back. Next it took 7 leaps forward and 8 leaps back. Finally, it took 4 more leaps forward before stopping.

a.Did the frog stop in front of or behind its starting point?
b. How many leaps away was it from its starting point?
c. How many times did it leap over the starting point?
d. How many leaps away was the frog from the starting point when it was furthest away?


~~~~Thank You~~~~

[Cheerfuldad]

Hi all,


Please help!

Q. Tank X and Y are each filled with some water. If water from Tank Y is poured into Tank X until the water in Tank X reaches the brim, there will be 8 litres of water left in Tank Y. If water from Tank X is poured into Tank Y until the water in Tank Y reaches the brim, there will be 26 litres of water left in Tank X. The ratio of the volume of Tank X to the volume of Tank Y is 5:3. How many more litres of water are needed to fill both tanks to their brim?

[tianzhu]

moonee:

:?: Hi can anyone help with this P5 question?


A frog took 5 leaps forward and 6 leaps back. Next it took 7 leaps forward and 8 leaps back. Finally, it took 4 more leaps forward before stopping.

a.Did the frog stop in front of or behind its starting point?
b. How many leaps away was it from its starting point?
c. How many times did it leap over the starting point?
d. How many leaps away was the frog from the starting point when it was furthest away?

Hi moonee

Good Evening.

You may use a heuristics known as Draw a Diagram to have a pictorial representation of the question.

a)The frog stopped in front of its starting point.
b)It was two leaps away from the starting point.
c)4 times
d)6 leaps

If you need the diagram, please let me know. I’ll do it tomorrow.

Best wishes

[tianzhu]

Cheerfuldad:

Hi all,


Please help!

Q. Tank X and Y are each filled with some water. If water from Tank Y is poured into Tank X until the water in Tank X reaches the brim, there will be 8 litres of water left in Tank Y. If water from Tank X is poured into Tank Y until the water in Tank Y reaches the brim, there will be 26 litres of water left in Tank X. The ratio of the volume of Tank X to the volume of Tank Y is 5:3. How many more litres of water are needed to fill both tanks to their brim?

Hi Cheerfuldad

Good Evening.

There is a similar question on page 238 of this thread. You may wish to refer to it.

http://www.kiasuparents.com/kiasu/forum/viewtopic.php?p=351164

Best wishes

[atutor2001]

tisha:

BTW, if the students draw some neat columns and do a few tabulations will it fetch any marks for the method :?:

Marks will only be given if the headings of the columns are relevant. BTW this question should not be solved by listing. It is by \"matching of factors\" of the number 50.