Q&A - PSLE Math

[zeepo]

tianzhu:

zeepo:

1) A fruiterer had the same number of apples, pears and lemons at first. After 98 lemons, some apples and pears were sold, there were 297 fruits left. There were twice as many apples as pears left. The number of lemons left was 13 fewer than the number of apples left. How many pears were sold?

Hi

Good Morning.

You may use MD or UP.

Hope this helps.

Best wishes

http://farm9.staticflickr.com/8516/8586859425_93a9627338_z.jpg\">

Thank you, tianzhu! Would appreciate if you could help me with the others, I am totally lost! Especially the one about the jigsaw puzzle!

[MathIzzzFun]

zeepo:

Hi, I am new to this forum. Would appreciate if someone could help me with the followings:


2) Anna and Ben take 9 days to complete a jigsaw puzzle. Ben and Celine take 3 days to complete the same jigsaw puzzle. When Celine partners with Dennis, they take 4 days to complete the jigsaw puzzle. How many days will Anna and Dennis take to complete 2 such jigsaw puzzles?

Thanks.

http://tinyurl.com/mathizzzfun-workrate03

cheers.

[Gin]

MathIzzzFun:

zeepo:

Hi, I am new to this forum. Would appreciate if someone could help me with the followings:


2) Anna and Ben take 9 days to complete a jigsaw puzzle. Ben and Celine take 3 days to complete the same jigsaw puzzle. When Celine partners with Dennis, they take 4 days to complete the jigsaw puzzle. How many days will Anna and Dennis take to complete 2 such jigsaw puzzles?

Thanks.

Thank you very much MathIzzFun :)! Appreciate your help!
http://tinyurl.com/mathizzzfun-workrate03

cheers.

[marstolive]

Thanks MathIzzzFun for the replies to the question! :grphug:

[tianzhu]

zeepo:

4) On Teachers' Day, a florist sold thrice as many roses as orchids and collected $703 in total. She collected $437 more for the roses than the orchids. Given that a stalk of rose cost $1.50 more than a stalk of orchid, find the cost of a stalk of orchid.

Hi

Good Morning.

Amount collected for roses ----- 570

Amount collected for orchid ----- 133

570/3 ----- 190

190 – 133 -----57

Number of orchid ----- 57/1.5 ----- 38

Cost of a stalk of orchid ------ 133/38 ------ 3.5

Best wishes

[tianzhu]

zeepo:

3) In a car park, there are thrice as many cars as vans. The number of cars is twice the number of motorcycles. The total number of wheels these vehicles have is 4598.

a) How many cars are parked at the car park?
b) If 1/3 of the motorcycles left the car park, how many vehicles are left in the car park?

Hi

Good Morning.

You may use the concept of “Grouping” or “Number*Value”.

Try to avoid working with decimals, therfore use 6u for cars.

Cars ----- 6u

Vans ----- 2u

Motorcycle ----- 3u

Consider number of wheels for a group of cars, vans and motorcycles.

(6*4) + (2*4) + (3*2) ------ 38

Number of groups ------ 121

Number of cars parked@carpark ----- 121*6 ----- 726

Number of motorcycles@carpark ------ 363

1/3 of motorcycles ------ 121

Number of vehicles@left at carpark ------- 726 + 242 + 242 -----1210

Best wishes

[zeepo]

tianzhu:

zeepo:

3) In a car park, there are thrice as many cars as vans. The number of cars is twice the number of motorcycles. The total number of wheels these vehicles have is 4598.

a) How many cars are parked at the car park?
b) If 1/3 of the motorcycles left the car park, how many vehicles are left in the car park?

Hi

Good Morning.

You may use the concept of “Grouping” or “Number*Value”.

Try to avoid working with decimals, therfore use 6u for cars.

Cars ----- 6u

Vans ----- 2u

Motorcycle ----- 3u

Consider number of wheels for a group of cars, vans and motorcycles.

(6*4) + (2*4) + (3*2) ------ 38

Number of groups ------ 121

Number of cars parked@carpark ----- 121*6 ----- 726

Number of motorcycles@carpark ------ 363

1/3 of motorcycles ------ 121

Number of vehicles@left at carpark ------- 726 + 242 + 242 -----1210

Best wishes

Thank you, tianzhu and Mathizzfun! Looks like I have lots to learn in order to help my daughter! Yuks!

[thisis2012]

MathIzzzFun:

zeepo:

Hi, I am new to this forum. Would appreciate if someone could help me with the followings:


2) Anna and Ben take 9 days to complete a jigsaw puzzle. Ben and Celine take 3 days to complete the same jigsaw puzzle. When Celine partners with Dennis, they take 4 days to complete the jigsaw puzzle. How many days will Anna and Dennis take to complete 2 such jigsaw puzzles?

Thanks.

http://tinyurl.com/mathizzzfun-workrate03

cheers.

why total amount of work -> 36 units?
thanks

[MathIzzzFun]

thisis2012:

MathIzzzFun:

[quote=\"zeepo\"]

Hi, I am new to this forum. Would appreciate if someone could help me with the followings:


2) Anna and Ben take 9 days to complete a jigsaw puzzle. Ben and Celine take 3 days to complete the same jigsaw puzzle. When Celine partners with Dennis, they take 4 days to complete the jigsaw puzzle. How many days will Anna and Dennis take to complete 2 such jigsaw puzzles?

Thanks.

http://tinyurl.com/mathizzzfun-workrate03

cheers.

why total amount of work -> 36 units?
thanks[/quote]lowest common multiple of 9,3 & 4 = 36

Alternatively, you can also work in fractions ..

in 1 day,
A + B --> 1/9 puzzle
B + C --> 1/3 puzzle
C + D --> 1/4 puzzle

A +D --> (1/9+1/3+1/4 - 2 x 1/3) puzzle = 1/36 puzzle

To complete 2 puzzles, A + D will take --> 2 ÷ 1/36 = 72 days

cheers.

[cimman]

zeepo:

3) In a car park, there are thrice as many cars as vans. The number of cars is twice the number of motorcycles. The total number of wheels these vehicles have is 4598.

a) How many cars are parked at the car park?
b) If 1/3 of the motorcycles left the car park, how many vehicles are left in the car park?

here's 2 methods for your child. In the first method, it uses traditional simultaneous equations. In the 2nd method, the u and p are made the same, this essentially eliminates one unknown early on in the process and thus leads to a simpler equation. However, both uses the same equations.

First, we transfer the values directly to the table:
http://i46.tinypic.com/2znwn6g.png\">

Method 1: then we fill up the blank boxes [red fonts] and circle the equations:
http://i48.tinypic.com/mlcoh.png\">

Method 2: here we process the middle row values first, by making u and p the same, which is the conventional approach. Why do we do this ? because this eliminates one unknown variable from a 2 unknown variable equation. Compare this to method 1 and you'll see how the 2 equations are derived.
The table gives a graphical view of all the relationships in the problem sum. All unit value questions or (number x group) questions can be represented in this table.
http://i49.tinypic.com/wsntle.png\">