Tutor MathsGuru: Ask me for your burning Maths questions!

[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=__ :___

[starlight1968sg]

super star:

pls help me with this problem


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

0.7 = 7/10 = 700/1000

7/8 = 875/1000

So the ratio is 700 : 875 = 28 : 35 = 4 : 5 :roll:

[starlight1968sg]

Tang:

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?

I don't understand that given solution too.

[maths6a]

super star:

pls help me with this problem


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

Let me try:=
2 : 3 is also equal to 2 divide by 3

so 0.7 : 7/8
= 7/10 divide by 7/8
= 7/10 x 8/7
= 4/5
= 4 : 5

another way is to make to common denomintaors:
7/10 : 7/8
= 28/40 : 35/40
= 28 : 35
= 4 : 5

AM I correct?
THanks

[Almighty]

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?

Hi Superstar,
Let me try:


Eliot can paint 1/3 of a room in 1 hr
Fred can paint 1/5 th of a room in 1 hr.
If they paint together:
in 1 hr they can paint 8/15 of a room
So,they will take 1 7/8 hrs to paint a room together.

[Almighty]

HI Dharma Sir,

Tom's mother told him to wash her car. She would pay him 10 cents on the first day and twice the amount of the previous day for the next 8 days.(edited for the typo error ) How much did Tom's mother pay him altogether?
Should we take the total number of days to be 8 or 9 days?
My method:
9 days - ans : $51.10
Book method:
8 days - ans: 25.50
If book answer is right,can u Please explain why it has to be taken as 8 days.
Thankyou