Tutor MathsGuru: Ask me for your burning Maths questions!

[Almighty]

singmathstutor:

Herbie:

I have one qn.


Can someone help me?

The no. shld be placed in a pyramid form.

TX

Row 1 2
Row 2 4 6 8
Row 3 10 12 14 16 18
Row 4 20 22 24 26 28 30 32

What is the largest no on Row 10?

288 is the largetst no. in a certain row. Which row is it?

One more method for your perusal: :idea:

\t1 X 2 = 2\t(1+1)x1
\t\t
\t2 X 4 = 8 \t( 2+2) X 2
\t\t
\t3 X 6 = 18 (3+3) X 3
\t\t
\tSo, ? =\t( 10+ 10) X10
a)\tAns = 200\t
\t\t
b) \t(12 + 12 ) X 12 = 288

[Dharma]

Almighty:

singmathstutor:

[quote=\"Herbie\"]I have one qn.


Can someone help me?

The no. shld be placed in a pyramid form.

TX

Row 1 2
Row 2 4 6 8
Row 3 10 12 14 16 18
Row 4 20 22 24 26 28 30 32

What is the largest no on Row 10?

288 is the largetst no. in a certain row. Which row is it?

One more method for your perusal: :idea:

\t1 X 2 = 2\t(1+1)x1
\t\t
\t2 X 4 = 8 \t( 2+2) X 2
\t\t
\t3 X 6 = 18 (3+3) X 3
\t\t
\tSo, ? =\t( 10+ 10) X10
a)\tAns = 200\t
\t\t
b) \t(12 + 12 ) X 12 = 288

[/quote]Welldone!

[Almighty]

Dharma:

Almighty:

Hi Dharma,


Question 11 also please.... AM i right for a)?? HOw 2 do (b) section.Stuck while finding the Diameter...



http://www.postimage.org/image.php?v=aVl5jjA

Part (a) is correct

Part (b)

Circumference of semi circle = 22cm ... Correct
2 sides of the square : 14cm x 2 = 28cm

Lastly, we need to find out the length of sides of the right angle triangle within the square.Let's call the side of the right angle triangle, \"a\"

We have 4 such right angle triangles in the square of sides 14cm. The right angle triangle has 2 sides of length a and the longer length is 14cm.

If we take 2 of the triangles and rearrange them to form a smaller square of side \"a\". Do the same for the other 2 triangles. We have 2 smaller squares of sides \"a\" and the total area of these 2 squares is the same as
the area if the larger square (196cm2)

2 x a x a =198 196 ? (Typo error ? )
a x a = 99 98
a = 9.95cm (calculator)then, 9.89.... (how to write this?round off 2 decimal point?)

Perimeter
= 22cm + 28cm + 9.95cm
= 59.95cm

Hi Dharma,
I did not understand the above thing in red...pl.clarify if my method below is wrong..
By the way, I have a different answer as given below. Please let me know whether i am right or wrong...


http://www.postimage.org/image.php?v=Ts5weFr

[Dharma]

Almighty:

Dharma:

[quote=\"Almighty\"]Hi Dharma,


Question 11 also please.... AM i right for a)?? HOw 2 do (b) section.Stuck while finding the Diameter...



http://www.postimage.org/image.php?v=aVl5jjA

Part (a) is correct

Part (b)

Circumference of semi circle = 22cm ... Correct
2 sides of the square : 14cm x 2 = 28cm

Lastly, we need to find out the length of sides of the right angle triangle within the square.Let's call the side of the right angle triangle, \"a\"

We have 4 such right angle triangles in the square of sides 14cm. The right angle triangle has 2 sides of length a and the longer length is 14cm.

If we take 2 of the triangles and rearrange them to form a smaller square of side \"a\". Do the same for the other 2 triangles. We have 2 smaller squares of sides \"a\" and the total area of these 2 squares is the same as
the area if the larger square (196cm2)

2 x a x a =198 196 ? (Typo error ? )
a x a = 99 98
a = 9.95cm (calculator)then, 9.89.... (how to write this?round off 2 decimal point?)

Perimeter
= 22cm + 28cm + 9.95cm
= 59.95cm

Hi Dharma,
I did not understand the above thing in red...pl.clarify if my method below is wrong..
By the way, I have a different answer as given below. Please let me know whether i am right or wrong...


http://www.postimage.org/image.php?v=Ts5weFr[/quote]Hi Almighty,

The correct way to calculate the perimeter of the shaded area is to use the original diagram.

You have done it correctly by calculating the arc lengths of the quadrant instead of the chord of the quadrant.

I was carried away with the transformed diagram in part (a). My apologies.

[Almighty]

Thanks Dharma!!!

[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.. :?

[MOE Hater]

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.. :?

Your method is the way I would go about it. Anyother forummers care to share their views?

[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