Q&A - PSLE Math

[MathIzzzFun]

jewelbox:

MathIzzzFun,

thanks for your explanation on vol. Now that i understand tt it is 'snail up and down' type qn, it helps in digesting the soln.

Also, appreciate your explanation to the qn on triangle on 19sep on why angle DEC is 3 units and so on. Thanks v much.

hope this helps..


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cheers.

[kwcllf]

MathIzzzFun:

zanen:

someone pls help Mr Tan drives from Town A to Town B, a distance of 720 km,at a constant speed. When he returns from Town B to Town A, he saves an hour of travel time by increasing his average speed by 10 km/h. Find the total time taken for the whole journey (to and fro).

720 km = 80 km/h x 9 h = 90 km/h x 8h
total time = 8h+9h =17h

cheers.

Hi sorry to bother.

Is there a more detailed or alternative explanation so that my DS can understand better?

Thanks

[tianzhu]

kwcllf:

Is there a more detailed or alternative explanation so that my DS can understand better?

Hi

This question is crafted in such a way that it’s pretty neat to use “Guess and Check” strategy.

Use it with logical reasoning. What are the usual speeds of cars travelling from point A to point B?

Plug the numbers in and you should be able to come up with a speed of 80km/h and 90km/h and a time difference of 1h.

Do not forget about “GC”, it might help us to gain some marks.

Another way is to use algebra if a child is well versed in it.

Best wishes

[fantasy1]

Hi


Can anyone help me with these 2 problems?

1)Last month,MAy spent 1/4 of her income on transport, 45% on food and saved the rest.
Her income was increased by 1/10 in this month.
Spent the same amount on transport but increased her savings by 30%.
She saved $780 this month.
(a) How much did she spend on food this month?


2)7 apples cost as much as 2 mongoes. 5 oranges cost as much as a mango.
Find the ratio of the cost of one applke to the cost of one mango to the cost of one orange.



Thank You

[fantasy1]

Hi


Can anyone help to solve these 2 maths problems?

1)Last month May spent 1/4 of her income on transport, 45% on food and saved the rest.
Her income was increased by 1/10 in this month.
She spent the same amount on transport but increased her savings by 30%.
She saved $780 this month.
(a) how much did she spend on food this month?

2)7 apples cost as much as 2 mangoes. 5 oranges cost as much as a mango. Find the ratio of the cost of one appl to the cost of one mango to the cost of one orange.


Thanbk You

[tianzhu]

fantasy1:

Hi


Can anyone help me with these 2 problems?

1)Last month,MAy spent 1/4 of her income on transport, 45% on food and saved the rest.
Her income was increased by 1/10 in this month.
Spent the same amount on transport but increased her savings by 30%.
She saved $780 this month.
(a) How much did she spend on food this month?


2)7 apples cost as much as 2 mongoes. 5 oranges cost as much as a mango.
Find the ratio of the cost of one applke to the cost of one mango to the cost of one orange.

Hi

1)

A neat way is to use MD.

Consider the savings this month.

13u ------ 780

10u ------- 600 (last month’s savings)

Last month

25% ------- transport

45% ------- food

30% -------- food

30% -------- 600

10% ------- 200

Income last month ------- 100% ------- 2000

Income this month ------- 2200

Transport ------- 500 (same amount)

Savings ------- 780

Food’s spending ------- 2200 – 500-780 ------- 920

2)

Use 70 units for the cost.

1 apple ------- 10 units

1 mango ------ 35 units

1 orange -------- 7 units

A : M: 0 ------- 10:35:7

Best wishes

[kwcllf]

Hi please help.


2 pieces of ribbon and 3 pieces of lace cost $10.
3 pieces of ribbon and 2 pieces of lace cost $y.
What is the total cost of 1 piece of ribbon and 1 piece of lace?
Give the answer in terms of y.


Thanks!

[fantasy1]

Hi

does anyone know how to solve ?

Thank You

[charsen]

kwcllf:

Hi please help.


2 pieces of ribbon and 3 pieces of lace cost $10.
3 pieces of ribbon and 2 pieces of lace cost $y.
What is the total cost of 1 piece of ribbon and 1 piece of lace?
Give the answer in terms of y.


Thanks!

Hi
This question can be solved using grouping method.

You can find the price of 5 pieces of ribbon and 5 pieces of lace,which is
$(10+y).
So cost of one ribbon and 1lace is
$(10+y)/5=(2+y/5)(ans)
Cheers.

[Michaelia0816]

Could anyone kindly help me to solve the question below, thx you.


Sani and Roney had a total of 398 game cards, Sani had 74 more game cards than Roney. After Roney had sold 25% fewer game cards than Sani, he had half as many game cards left as Sani. How many game cards had Roney left?