Tutor MathsGuru: Ask me for your burning Maths questions!

[mathsguru]

super star:

Hi Mathsguru

thanks for ur help.I have another problem pls help to solve this
Aurdrey & belle have some money each.If audrey spends $18 &belle spends $24 each day,audrey will still have $25 left when belle has spent all her money.If audrey spends $13 &bellespends $30each day,audrey will have $139 left when belle has spent all her money.How much money do they have altoghter?

Hi Superstar,

Here's my solution. Very sorry for the delay!


MathsGuru

http://www.postimage.org/image.php?v=PqGGeoS

[mathsguru]

Almighty:

Hi all,


This is a problem already posted earlier in this forum n solved.
But i hv a doubt in this solution.

The problem :

During a sale, the price of a skirt was reduced from $256.80 to
$214 inclusive of GST of 7%. What was the decrease in price of the skirt, excluding GST?

Forum answer: (Dont remember who answered...Pl.forgive)

Skirt before GST before discount = 256.80*0.93= 238.82\t\t\t\t\t\t\t
Skirt before GST after discount = 214*0.93 = 199.02\t\t\t\t\t\t\t

Decrease in skirt before GST = $39.80 (Ans in 2 significant figure, then $40)

In one step will be, discount excluding GST = (256.8-214)*0.93 = $39.80

My solution:
Before discount and GST:\t\t
107% ---- 256.80 \t\t
100% ---- ? (240)\t\t
\t\t
After Discount and GST\t\t
107% ----214\t\t
100% -------? ($40)\t\t
(OR ) ONE STEP SOLUTION:\t\t
\t\t
107% --- 42.80 ( 256.80 - 214)\t\t
100% --- ?\t\t
\t\t
Ans = $40\t\t

Can anyone clarify which is correct? If i'm wrong please let me know why i should not assume in my way.. :?

Hi Almighty,

I would do it your way too. This is because GST is an additional tax on top of the original price. Hence, the price including GST is 107% of the original price. We should not use the price including GST to be 100% because in this way, the original price is 93% only, which is not right.

I always show my receipts to my students to demonstrate this concept. You can take a look at some receipts you have too! F&B receipts are clearer and easier to understand. For instance, a chicken chop set cost $10. Service charge is an additional 10% on that --> $1. Subtotal before GST is $11. Remember GST is Goods AND Services Tax --> so this tax is levied on both the chicken chop as well as the service charge that you paid. Hence, final amount = 1.07 x $11 = $11.77.

Hope this helps!


MathsGuru

[mathsguru]

itro:

Hi,


I have a question on understanding \"between\" when it is used in Math questions. Sometimes, \"between An and B\" does not include A and B, but sometimes it does. When we say a number between 10 an 20, the number should not be 10 nor 20. Could you please advise whether I should include 12 noon and 11 o'clock at night when solving the following problem and why?

The grandfather's clock chimes once when it is 1 o'clock, chimes twice when it is 2 o'clock, chimes thrice when it is 3 o'clock and so forth. How many times will it chime between 12 noon and 11 o'clock at night?

Hi Itro,

In the above question, I would take it to exclude 12 noon and 11pm. So, actually, the question is asking for 1 + 2 + 3 + 4 + 5 + ... + 9 + 10.
It's testing students the summation of numbers. Answer should be 55 times.

I guess when the word \"between\" is used, we have to \"analyse\" and see if it's used figuratively or literally.

Figuratively when it's used to describe a scenario. For instance, share 100 marbles between A & B. A task is shared between 2 workers. In such cases, we usually divide the total by 2 (or according to how they portion the items/task). The word \"between\" is used for 2 people/items while the word \"among\" is used for more than 2 people/items.

Literally when it's used to indicate the no. of things/distance/intervals/etc between 2 objects/places/persons/markers/etc. Basically, we can \"literally\" count the no. of things/distance/intervals/etc which exist or are placed between the 2 objects/places/persons/markers/etc. Hence, it makes sense for us to not include the 2 objects/places/persons/markers/etc, unless the question specifically mentions so.

In the above question, it is the \"literal\" interpretation --> the no. of chimes between 12 noon and 11pm. 12 noon and 11 pm are used as markers and they should not be included.

As for Coffeecat's suggestion to include the chimes of 12 noon (which will logically still take place seconds after 12 noon), I think we can interpret it simply. This is because the question did not mention how long each chime will take, so I don't think the question is expecting us to go so deep into that level.

Just my 2 cent's worth based on my experience so far...


MathsGuru

[Cheerfuldad]

Dear all,


Please help!

Two P5 challenging questions:

Q1 There are an equal number of boys in classes 6A and 6B. 3/4 of the pupils in Class 6A are boys and 1/7 of the pupils in Class 6B are girls. Given that the two classes have a total of 12 girls, how many pupils are there in each class?

Q2 In a theatre, when a boy sits down, the number of boys standing up becomes 4/5 of the number of girls standing up. On the other hand, when a girl sits down, the number of girls standing up become 8/7 of the number of boys standing up. How many boys and girls are there in the theatre?

Look forward to your reply.

TIA

[Almighty]

mathsguru:

Almighty:

Hi all,


This is a problem already posted earlier in this forum n solved.
But i hv a doubt in this solution.

[My solution:
Before discount and GST:\t\t
107% ---- 256.80 \t\t
100% ---- ? (240)\t\t
\t\t
After Discount and GST\t\t
107% ----214\t\t
100% -------? ($40)\t\t
(OR ) ONE STEP SOLUTION:\t\t
\t\t
107% --- 42.80 ( 256.80 - 214)\t\t
100% --- ?\t\t
\t\t
Ans = $40\t\t

Hi Almighty,

I would do it your way too. This is because GST is an additional tax on top of the original price. Hence, the price including GST is 107% of the original price. We should not use the price including GST to be 100% because in this way, the original price is 93% only, which is not right.

I always show my receipts to my students to demonstrate this concept. You can take a look at some receipts you have too! F&B receipts are clearer and easier to understand. For instance, a chicken chop set cost $10. Service charge is an additional 10% on that --> $1. Subtotal before GST is $11. Remember GST is Goods AND Services Tax --> so this tax is levied on both the chicken chop as well as the service charge that you paid. Hence, final amount = 1.07 x $11 = $11.77.

Hope this helps!


MathsGuru

[quote = \"moe Hater\"]
Your method is the way I would go about it. Anyother forummers care to share their views?

Thank you MOE Hater and Math Guru...

[mathsguru]

Cheerfuldad:

Dear all,


Please help!

Two P5 challenging questions:

Q1 There are an equal number of boys in classes 6A and 6B. 3/4 of the pupils in Class 6A are boys and 1/7 of the pupils in Class 6B are girls. Given that the two classes have a total of 12 girls, how many pupils are there in each class?

Q2 In a theatre, when a boy sits down, the number of boys standing up becomes 4/5 of the number of girls standing up. On the other hand, when a girl sits down, the number of girls standing up become 8/7 of the number of boys standing up. How many boys and girls are there in the theatre?

Look forward to your reply.

TIA

Hi Cheerfuldad,

Here are my solutions. Hope they are clear enough for you and your child to understand!


MathsGuru

http://www.postimage.org/image.php?v=Ts91DYi

http://www.postimage.org/image.php?v=Ts91Gsr

[Cheerfuldad]

mathsguru:

Cheerfuldad:

Dear all,


Please help!

Two P5 challenging questions:

Q1 There are an equal number of boys in classes 6A and 6B. 3/4 of the pupils in Class 6A are boys and 1/7 of the pupils in Class 6B are girls. Given that the two classes have a total of 12 girls, how many pupils are there in each class?

Q2 In a theatre, when a boy sits down, the number of boys standing up becomes 4/5 of the number of girls standing up. On the other hand, when a girl sits down, the number of girls standing up become 8/7 of the number of boys standing up. How many boys and girls are there in the theatre?

Look forward to your reply.

TIA

Hi Cheerfuldad,

Here are my solutions. Hope they are clear enough for you and your child to understand!


MathsGuru

http://www.postimage.org/image.php?v=Ts91DYi

http://www.postimage.org/image.php?v=Ts91Gsr

Hi MathsGuru,

Thank you very much! I can use your solutions to share with my child.

Regards
Cheerfuldad

[itro]

Thanks for your detailed info.


The question is from Math Olympiad for P3 and P4, as I mentioned in a followup message. The correct answer from the book indicates inclusion of 12 noon and 11pm. This confuses me and my child as well. I would like to suggest teachers 9especially those who create exam papers) to use something like \"from 12 noon to 11pm\" if the markers or boundaries are expected to be included.

mathsguru:

itro:

Hi,

I have a question on understanding \"between\" when it is used in Math questions. Sometimes, \"between An and B\" does not include A and B, but sometimes it does. When we say a number between 10 an 20, the number should not be 10 nor 20. Could you please advise whether I should include 12 noon and 11 o'clock at night when solving the following problem and why?

The grandfather's clock chimes once when it is 1 o'clock, chimes twice when it is 2 o'clock, chimes thrice when it is 3 o'clock and so forth. How many times will it chime between 12 noon and 11 o'clock at night?

Hi Itro,

In the above question, I would take it to exclude 12 noon and 11pm. So, actually, the question is asking for 1 + 2 + 3 + 4 + 5 + ... + 9 + 10.
It's testing students the summation of numbers. Answer should be 55 times.

I guess when the word \"between\" is used, we have to \"analyse\" and see if it's used figuratively or literally.

Figuratively when it's used to describe a scenario. For instance, share 100 marbles between A & B. A task is shared between 2 workers. In such cases, we usually divide the total by 2 (or according to how they portion the items/task). The word \"between\" is used for 2 people/items while the word \"among\" is used for more than 2 people/items.

Literally when it's used to indicate the no. of things/distance/intervals/etc between 2 objects/places/persons/markers/etc. Basically, we can \"literally\" count the no. of things/distance/intervals/etc which exist or are placed between the 2 objects/places/persons/markers/etc. Hence, it makes sense for us to not include the 2 objects/places/persons/markers/etc, unless the question specifically mentions so.

In the above question, it is the \"literal\" interpretation --> the no. of chimes between 12 noon and 11pm. 12 noon and 11 pm are used as markers and they should not be included.

As for Coffeecat's suggestion to include the chimes of 12 noon (which will logically still take place seconds after 12 noon), I think we can interpret it simply. This is because the question did not mention how long each chime will take, so I don't think the question is expecting us to go so deep into that level.

Just my 2 cent's worth based on my experience so far...


MathsGuru

[clblinym]

Dear all,


Please help!

Find the value of 64X46+73X37+82X28

Is there any special technique to solve this math problem?

Thanks a lot.

[super star]

thanks maths guru.

mathsguru:

super star:

Hi Mathsguru

thanks for ur help.I have another problem pls help to solve this
Aurdrey & belle have some money each.If audrey spends $18 &belle spends $24 each day,audrey will still have $25 left when belle has spent all her money.If audrey spends $13 &bellespends $30each day,audrey will have $139 left when belle has spent all her money.How much money do they have altoghter?

Hi Superstar,

Here's my solution. Very sorry for the delay!


MathsGuru

http://www.postimage.org/image.php?v=PqGGeoS