Q&A - PSLE Math

[isetan]

Hi, appreciate help into this question:-


Lawerance had some money. He spent 3/5 of it on 4 similar highlighters. With the rest of his money, he bought another 2 such highlighters and 10 rulers.

a) What fraction of his money was spent on buying 10 rulers? Give your ans
in its simplest form.

b) In a sale, Lawerance would be given 1 free ruler for every 12 rulers bought. how many rulers would he get altogether if he had spent all money at first on rulers?


DD has worked out answer for (a) is 1/10 and (b) is 91.

Wonder if her answer is correct?

TIA

[tianzhu]

isetan:

Hi, appreciate help into this question:-


Lawerance had some money. He spent 3/5 of it on 4 similar highlighters. With the rest of his money, he bought another 2 such highlighters and 10 rulers.

a) What fraction of his money was spent on buying 10 rulers? Give your ans
in its simplest form.

b) In a sale, Lawerance would be given 1 free ruler for every 12 rulers bought. how many rulers would he get altogether if he had spent all money at first on rulers?


DD has worked out answer for (a) is 1/10 and (b) is 91.

Wonder if her answer is correct?

TIA

Hi

I've the same answer for (a).

12 units ------ 4 highlighters

3 units ------ 1 highlighter

2 units ------ 10 rulers

2/20 ------ 1/10

For (b), my answer is 108.

2 units ------- 10 rulers

20 units ------ 100 rulers

1 free ruler for every 12 rulers bought.

96 + 8 + 4 ------ 108

Best wishes

[isetan]

thanks Tianzhu. Appreciate your help.

[isetan]

tianzhu:

isetan:

Hi, appreciate help into this question:-


Lawerance had some money. He spent 3/5 of it on 4 similar highlighters. With the rest of his money, he bought another 2 such highlighters and 10 rulers.

a) What fraction of his money was spent on buying 10 rulers? Give your ans
in its simplest form.

b) In a sale, Lawerance would be given 1 free ruler for every 12 rulers bought. how many rulers would he get altogether if he had spent all money at first on rulers?


DD has worked out answer for (a) is 1/10 and (b) is 91.

Wonder if her answer is correct?

TIA

Hi

I've the same answer for (a).

12 units ------ 4 highlighters

3 units ------ 1 highlighter

2 units ------ 10 rulers

2/20 ------ 1/10

For (b), my answer is 108.

2 units ------- 10 rulers

20 units ------ 100 rulers

1 free ruler for every 12 rulers bought.

96 + 8 + 4 ------ 108

Best wishes

Tianzhu,

Just clarify again....for the last sentence, why do you need to 'plus 4' (ie. 96+8+4).

thanks.

[tianzhu]

isetan:

Tianzhu,

Just clarify again....for the last sentence, why do you need to 'plus 4' (ie. 96+8+4).

thanks.

Hi

He can buy 100 rulers.

1 free ruler for every 12 rulers bought.

100 = 96 + 4

For 96 rulers, he gets 8 free

So, (96 + + 4 ------- 108

Best wishes

[isetan]

Thanks! Understand now.

[kiasustar]

Hi anyone can help?


The average height of a group of children was 139.4 cm. When Mr Tan measured and recorded the height of these children, he wrongly recorded one child's height as 192 cm when it shld have been 129 cm. As a result, Mr Tan recalculated the average height as 142.4 cm. How many children were there in the group?

:rahrah: :thankyou:

[isetan]

Hi, need help on this question:--



http://i50.tinypic.com/1g65hi.jpg\">

Two candles of different thickness were placed on a table. Candle B was placed on a stand of height 8 cm to reach the same height as Candle A. At 0630, Candle A was lit. One hour later, Candle B was lit. Both candles burnt down to the height marked 'X' at 1100. At 1600, Candle B burnt out while Candle A only burnt out at 2000. The rate of burning for each candle was constant throughtout.

(a) Find the ratio of the time taken for Candle A to burn to \"X\" to the time taken for Candle B to burn to \"X\".

(b) Find the original height of Candle A.

TIA.

[MathIzzzFun]

kiasustar:

Hi anyone can help?


The average height of a group of children was 139.4 cm. When Mr Tan measured and recorded the height of these children, he wrongly recorded one child's height as 192 cm when it shld have been 129 cm. As a result, Mr Tan recalculated the average height as 142.4 cm. How many children were there in the group?

:rahrah: :thankyou:

Hi
Total increase in overall height
= 192-129 = 63
= increase in average height x number of children
increase in average height = 142.4-139.4=3
Number of children =63/3 = 21

cheers.

[MathIzzzFun]

isetan:

Hi, need help on this question:--



http://i50.tinypic.com/1g65hi.jpg\">

Two candles of different thickness were placed on a table. Candle B was placed on a stand of height 8 cm to reach the same height as Candle A. At 0630, Candle A was lit. One hour later, Candle B was lit. Both candles burnt down to the height marked 'X' at 1100. At 1600, Candle B burnt out while Candle A only burnt out at 2000. The rate of burning for each candle was constant throughtout.

(a) Find the ratio of the time taken for Candle A to burn to \"X\" to the time taken for Candle B to burn to \"X\".

(b) Find the original height of Candle A.

TIA.

Hi

I presume you are able to work out (a)

Time taken for A to burn to X --> 4.5h
Time taken for B to burn to X --> 3.5h
Total time taken for A to burn out --> 13.5h
Total time taken for B to burn out --> 8.5h
4.5/13.5 A = 3.5/8.5 B
A/B = 21/17
A --> 21 units, B --> 17 units
4 units --> 8 cm
So, original height of A --> 21/4 x 8 = 42 cm

cheers.