Tutor MathsGuru: Ask me for your burning Maths questions!

[firebird]

Dear Yu Xuan


Thank you very much for you answer.

With best regards
firebird

[Dharma]

firebird:

Dear Maths guru


Good evening.

Please help me on the following:

The sum of 4 numbers is 80.
If you add 3 to the first number, subtract 3 from the second number, multiply the third number by 3 and divide the fourth number by 3, the result will be equal.
What is the difference between the largest and the smallest of the original numbers?

Thank you
firebird

A + B + C + D = 80
A + 3 = B – 3 = 3C = D/3

A = 3C – 3
B = 3C + 3
D = 9C

(3C – 3) + (3C + 3) + C + 9C = 80
16C = 80
C = 5

A = 15 – 3 = 12
B = 15 + 3 = 18
C = 5
D = 45

Difference between the largest and smallest of the original numbers = D – C = 45 – 5 = 40

[Herbie]

Dear Dharma


I have one qn which i need yr help.

RGPS paper 2 Q 15. is a square embeded into a circle and the area of the square is 400sqm. Qn required us to find the shaded area between the square and circle.

The given answer is 228.32. However if the child uses the a2 + b2 = c2 he will derive at 228.38cm2.

Would you able to advise whether the answer 228.38 cm2 can be marked correct as well.

Tq

[Dharma]

Herbie:

Dear Dharma


I have one qn which i need yr help.

RGPS paper 2 Q 15. is a square embeded into a circle and the area of the square is 400sqm. Qn required us to find the shaded area between the square and circle.

The given answer is 228.32. However if the child uses the a2 + b2 = c2 he will derive at 228.38cm2.

Would you able to advise whether the answer 228.38 cm2 can be marked correct as well.

Tq

Hi Herbie,

I guess it will not make a difference which methed is used to find the diameter of the circle; either by Pythagoras Theorem or just from the Area of the Square (given)

The difference in the answer in the number of decimals places will depend on what one uses as pi.
If qns says pi = 3.142 or 22/7 then do what the question says.
If qn is silent about the value of pi, then use the pi button on the calculator.


http://www.postimage.org/image.php?v=Tst2900

[Herbie]

hi Dharma,


If the qn is silent abt the pi, it is possible for us to key into the calculator 22/7 and it is for calculation?

i dun know why but 22/7 = 3.142857143 whereas the pi the calculator is 3.141592654.

My son used 22/7 for his calculation and his school teacher marked his answer 228.38 as incorrect.

What is yr view on this???

Many thanks!

[Dharma]

Herbie:

hi Dharma,


If the qn is silent abt the pi, it is possible for us to key into the calculator 22/7 and it is for calculation?

i dun know why but 22/7 = 3.142857143 whereas the pi the calculator is 3.141592654.

My son used 22/7 for his calculation and his school teacher marked his answer 228.38 as incorrect.

What is yr view on this???

Many thanks!

If the qn is silent; then use the pi sign in the calculator.
You should use 22/7 only when the question says (pi = 22/7) or use 3.142 when qns says (pi = 3.142)

To be safe, just follow the instructions. The accuracy in the answer to decimal places may be important now with the introduction of calculators for paper 2.

Anyway, I'm just a parent. You may wish to check with your son's maths teacher on this just to be doubly sure.

[Muffins]

Dharma is completely right. For a test, I had put my answer as 60.22, because I had used 22/7, but the answer was 60.21, and I had lost the 4 marks. So, it is better to check the question before...

[Tang]

Dharma:

Yu Xuan:

[quote=\"Dharma\"]
Mass of all 5 boys
= (105 + 113 + 116 + 117 + 118 + 124 + 125 + 130 + 137 + 139)/4
= 306

Sum of the mass of the 2 lightest boys and 2 heaviest boys
= 105 + 139
= 244

The mass of the 3rd heaviest boy = 306 – 244 = 62

cracking my head on how I should proceed after getting 306.

I surelyyou.

Hi Yu Xuan,

Thanks but I am actually learning from all of you everyday and I hope that our sharing will be truly beneficial to parents and their P6 kids in this coming PSLE Maths exam.[/quote]
Hi,

A - largest, E - smallest

A + B = 139

A + C = 137

Based on answer above C = 62, so A = 137 - 62 = 75

and B = 139 - 75 = 64


E + D = 105

E + C = 113

Similarly, E = 113 - 62 = 51 and D = 105 - 51 = 54

A, B, C, D, E --> 75, 64, 62, 54, 51

However the mass of 2 are:

139, 137, 129, 126, 126, 118, 116, 115, 113 and 105

These do not tally with those numbers given in the question.

Any comments?

[super star]

hi maths guru

please help me with this problem.
Eliot can paint a room in 3 hrs.fred can paint the same room in 5 hrs.how long will they take to paint the room if they do it together?

[super star]

pls help me with this problem


fill in the blank
0.7:7/8=__ :___