Tutor MathsGuru: Ask me for your burning Maths questions!

[YLH88]

Hi Dharma,


Thank you very much!

[rubydoll]

Good morning.


Kindly help on the following maths sums:

1) The lengths of two rectangles are 11m and 19m respectively. Their total area is 321meter square. What is the diferrence in their areas?

2)Mrs Tan had $800 at first. 80% of her money consisted of $5 notes and the rest were $10 notes. After she spend some $5 notes, the remaining $5 notes was 60% of the money she had left. How much did Mrs Tan spend?

3)There are 147 pages in a science textbook. What is the total number of digits on all the pages of the textbook.

4)A group of people went hunting. On the average, 6 people hunted 5 rabbits, 15 people hunted 2 deer and 10 people hunted 1 buffalo. The total number of animals hunted was 6 more than the total number of people who went hunting. How many people went hunting?

Many thanks for your help
rubydoll

[Dharma]

rubydoll:

Good morning.


Kindly help on the following maths sums:

1) The lengths of two rectangles are 11m and 19m respectively. Their total area is 321meter square. What is the diferrence in their areas?

2)Mrs Tan had $800 at first. 80% of her money consisted of $5 notes and the rest were $10 notes. After she spend some $5 notes, the remaining $5 notes was 60% of the money she had left. How much did Mrs Tan spend?

3)There are 147 pages in a science textbook. What is the total number of digits on all the pages of the textbook.

4)A group of people went hunting. On the average, 6 people hunted 5 rabbits, 15 people hunted 2 deer and 10 people hunted 1 buffalo. The total number of animals hunted was 6 more than the total number of people who went hunting. How many people went hunting?

Many thanks for your help
rubydoll

Hi rubydoll,

Q4 does not seem like PSLE kind of Qn. Do u know the answer?

1)\tThe lengths of two rectangles are 11m and 19m respectively. Their total area is 321meter square. What is the difference in their areas?

There are 2 unknowns with 1 equation…. Need to solve by trial and error.
11 x W1 + 19 x W2 = 321
11W1 + 19W2 = 321

W1 = 5 & W2 = 14 (trial & error)

Difference in area = (19x14) – (11x5) = 211m2

2)\tMrs Tan had $800 at first. 80% of her money consisted of $5 notes and the rest were $10 notes. After she spent some $5 notes, the remaining $5 notes was 60% of the money she had left. How much did Mrs Tan spend?

80% of money - $640 ($5 notes)
20% of money - $160 ($10 notes)

After spending some $5 notes, the remaining $10 notes were 40% of money left.

40% - $160
20% - $80
60% - $240

Amt of money spent = $640 - $240 = $400

3)There are 147 pages in a science textbook. What is the total number of digits on all the pages of the textbook.

Pages 1 ~ 9 ….. 9 digits
Pages 10 ~ 99 … (99-10+1)x 2 = 180 digits
Pages 100 ~ 147 … (147 – 100 + 1) x 3 = 144 digits

Total no. of digits = 9 + 180 + 144 = 333

4) A group of people went hunting. On the average, 6 people hunted 5 rabbits, 15 people hunted 2 deer and 10 people hunted 1 buffalo. The total number of animals hunted was 6 more than the total number of people who went hunting. How many people went hunting?

On an average;
6 people hunted 5 rabbits; 1 person hunted 5/6 rabbit (sound ridiculous)
15 people hunted 2 deers; 1 person hunted 2/15 deer
10 people hunted 1 buffalo; 1 person hunted 1/10 buffalo

Therefore, we can say that 1 person can hunt 5/6 of a rabbit , 2/15 of a deer, 1/10 of a buffalo (or a combination of all three)

30 persons can therefore hunt 25 rabbits, 4 deers & 3 buffaloes (Total = 32 animals)
There are 2 more number of animals hunted compared to the number of hunters (32 – 30 = 2)

Therefore; in order to have 6 more number of animals hunted compared to the number of hunters; there must be (30 x 3 = 90 hunters)

96 animals – 90 hunters = 6

[fudgemum]

Dharma:

1)\tThe lengths of two rectangles are 11m and 19m respectively. Their total area is 321meter square. What is the difference in their areas?

There are 2 unknowns with 1 equation…. Need to solve by trial and error.
11 x W1 + 19 x W2 = 321
11W1 + 19W2 = 321

W1 = 5 & W2 = 14 (trial & error)

Difference in area = (19x14) – (11x5) = 211m2

Hi Dharma,

If I do remember correctly these questions are from Rulang Primary CA1 2009 test paper. Technically there is one more answer to the above question.
24*11 +3*19 = 321
24*11 - 3*19 = 207.
But in this case the breadth (24) is bigger than the length (11).

[Dharma]

fudgemum:

1)\tThe lengths of two rectangles are 11m and 19m respectively. Their total area is 321meter square. What is the difference in their areas?

There are 2 unknowns with 1 equation…. Need to solve by trial and error.
11 x W1 + 19 x W2 = 321
11W1 + 19W2 = 321

W1 = 5 & W2 = 14 (trial & error)

Difference in area = (19x14) – (11x5) = 211m2

Thanks fudgemum. Strange that a qn can be set with more than 1 answer.

[fudgemum]

Hi,


I am not able to draw the picture.There are three identical circles A, B and C. The circumference of each circle passes through the centre of the other two circles. So we have regions like
A only, B only, C only,
A and B only, B and C only, A and C only,
A and B and C (center portion).

How do you proove that
A and B only, B and C only, A and C only (i.e A insersection B, B intersection C , and C intersection A)
this area is half of the circle.
TIA

[Dharma]

fudgemum:

Hi,


I am not able to draw the picture.There are three identical circles A, B and C. The circumference of each circle passes through the centre of the other two circles. So we have regions like
A only, B only, C only,
A and B only, B and C only, A and C only,
A and B and C (center portion).

How do you proove that
A and B only, B and C only, A and C only (i.e A insersection B, B intersection C , and C intersection A)
this area is half of the circle.
TIA

Hi fudgemum,

Hope this what u r asking.


http://www.postimage.org/image.php?v=Pqn_P8A

[rubydoll]

Kindly refer to the 4 questions posted by me on 17/2/2010.


1) The answer given to question number 4 is 90 people. Therefore, the working and the answer is correct.

2) All the four questions are from Rulang Primary School, Primary 6 CA assessment Paper 2 for 2009.

3) Many many thanks for the help

With best regards
Ruby Doll

[tianzhu]

2)Mrs Tan had $800 at first. 80% of her money consisted of $5 notes and the rest were $10 notes. After she spend some $5 notes, the remaining $5 notes was 60% of the money she had left. How much did Mrs Tan spend? How much did Mrs Tan spend?


Hi Dharma

This question is from Rulang CA1 2009.
http://www.orlesson.org/orp/09Ma/2009-P6-Math-CA1-Rulang.pdf

The answer hinges on the interpretation of this sentence.

After she spent some $5 notes, the remaining $5 notes was 60% of the money she had left.

Does it refer to the physical number of notes or its value?

Best wishes

[ooptimizer]

She spent $400.