Q&A - PSLE Math

[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\">

[Beikiasu]

Hi, can someone help me to solve this problem sum? SCG, 2011,

SA 1, Question 18, 5 mark. Answer $105. Thanks.

Gina, Mary and Alyssa have some money. They want to buy a handbag for their mother. Gina has $30 more than Mary.

If Gina buys the handbag, the ratio of her money left to that of Mary and Alyssa is 9:24:27 respectively.
If Mary buys the same handbag, the ratio of her money left to that of Gina and Alyssa is 1:10:9 respectively.
If Alyssa buys the same handbag, the ratio of her money left to that of Gina and Mary is 1:5:4 respectively.
What is the cost of the handbag?

[MathIzzzFun]

Beikiasu:

Hi, can someone help me to solve this problem sum? SCG, 2011,

SA 1, Question 18, 5 mark. Answer $105. Thanks.

Gina, Mary and Alyssa have some money. They want to buy a handbag for their mother. Gina has $30 more than Mary.

If Gina buys the handbag, the ratio of her money left to that of Mary and Alyssa is 9:24:27 respectively.
If Mary buys the same handbag, the ratio of her money left to that of Gina and Alyssa is 1:10:9 respectively.
If Alyssa buys the same handbag, the ratio of her money left to that of Gina and Mary is 1:5:4 respectively.
What is the cost of the handbag?

discussed on pg 573-
http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=280&start=5720

cheers.

[Beikiasu]

Thanks Mathlzfun! :thankyou:


May I know where the cost of handbag --21u come from?

[MathIzzzFun]

Beikiasu:

Thanks Mathlzfun! :thankyou:


May I know where the cost of handbag --21u come from?

total amount left will be the same in case.

depending on which person buys the bag, the amount left by that person will be reduced by the number units equal to cost of handbag

gina has 30u, if she buys handbag, she is left with 9u, handbag--> 21u

alyssa has 27u, if she buys handbag, she is left with 6u, handbag --> 21u

mary has 24u, if she buys handbag, she is left with 3u, handbag --> 21u

cheers.