Tutor MathsGuru: Ask me for your burning Maths questions!

[CJM]

atutor2001:

small:

[quote=\"CJM\"]To motivate her son to study mathematics, Mrs Mani agreed to reward her son 50 cents for every problem solved correctly and to fine him 35 cents for each incorrect solution. At the end of 17 problems, neither owed anything to the other. How many problems did her son solve correctly?

Please try to use guess and check method.

From working,her son solved 7 problemd correctly.

I recommend \"replacement method\". This is a 3 mark question and guess and check might take too much time.

If the son gets all correct : 17 x 50 = 850
For every 1 wrong, the son must return 50 + fine 35 = 85

At the end, the son gets nothing means he return 85 cents 10 times. (850/85 = 10) That is, he got 10 wrong. Therefore, no. of correct is 7.[/quote]thanks so much ... my ds' answer is correct : ) i m not sure how to do the sums so consulted you all, the math expert to get the answer

[CJM]

small:

CJM:

To motivate her son to study mathematics, Mrs Mani agreed to reward her son 50 cents for every problem solved correctly and to fine him 35 cents for each incorrect solution. At the end of 17 problems, neither owed anything to the other. How many problems did her son solve correctly?

Please try to use guess and check method.

From working,her son solved 7 problemd correctly.

thanks : )
ds uses the guess n check method :

correct / incorrect / Total / Check
8 9 0.85 cross

7 10 0 tick

the answer is 7

[kwcllf]

atutor2001:

meimeitan:

hi


Then, may I know answer for that question:

There were 12 more girls than boys in a club. 1/3 of the girls and 1/4 of the boys took part in a competition. Among those who took part in the competition, there were 6 more girls than boys. What fraction of the club members who did not take part in the competition were boys?

Thanks.

Let girls be 3U
Girls taking part in competition will be 1U

Let boys be 4V
Boys taking part in competition will be 1V

There were 12 more girls than boys in a club: 3U = 4V + 12 ----> (1)
Those who took part in the competition, there were 6 more girls than boys : 1U = 1V + 6 ----> (2)

(2)x 3 : 3U=3V+18 ----> (3)

Put (3) into (1) : 3V+18 = 4V+12 --> 1V = 6

From (2) : 1U = 6+6 = 12

No of boys who did not take part : 3V = 3x6 = 18
Total club members = 3U + 4V = 3x12 + 4x6 = 36+24 = 60

Fraction of the club members who did not take part in the competition were boys : 18/60 = 3/10

G [][][][][][][][][][][][][4][4][4]
B [][][][][][][][][][][][]

Convert both fractions to a common denominator.
Girls: 1/3 change to 4/12
Boys: 1/4 change to 3/12

The 12 extra Girls, divide them into 3 parts of [4]

From the above model:

1/3 Girls = 4 [] + 4

1/4 Boys = 3 []

Since there are 6 more Girl than Boys who took part in the competition.

1 [] = 6 – 4 = 2


Total number of [] = 12 x 2 = 24

Total number of Boys and Girls = 24 x 2 + 12 = 60

Therefore,
Number of Boys that did not take part in the competition = 9 x 2 = 18
Fraction of Boys that did not take part in the competition = 18/60 = 3/10

[Muffins]

meimeitan:

hi


Then, may I know answer for that question:

There were 12 more girls than boys in a club. 1/3 of the girls and 1/4 of the boys took part in a competition. Among those who took part in the competition, there were 6 more girls than boys. What fraction of the club members who did not take part in the competition were boys?

Thanks.

Let the boys be ϰ, and the girls be ϰ + 6

So ϰ X 4 = 4ϰ (total number of boys in the club)

(ϰ+6) X 3 = 3ϰ + 18 (total number of girls)

3ϰ + 18 = 4ϰ + 12

18 = ϰ + 12

∴ ϰ = 6

Total number of members who did not take part in the competition: 5ϰ + 12

Boys who did not take part: 3ϰ

(5ϰ+12) - 3ϰ = 2ϰ + 12

6 X 3 = 18

6 X 5 = 30

30 + 12 = 42

18/42 = 3/7

Hmm.... My working seems correct. However, you guys' answers are 3/10 though... any ideas or advice?

P.S.
Total number of boys in club = 24
Total number of girls in club = 36

[pixiedust]

Please help me with this P5 question.

Ratio not covered yet so prefer solution without using ratio. Thanks


Nancy has 3 times as many buttons as Mary.
Every day, Mary uses 5 buttons and Nancy uses 4 buttons.
When Mary has finished using all her buttons, Nancy has 88 buttons left.
(1) How many days does Mary take to use all her buttons ?
(2) How many buttons are there altogether at first ?

[ADoc]

Muffins:

...

Total number of members who did not take part in the competition: 5ϰ + 12

Boys who did not take part: 3ϰ

(5ϰ+12) - 3ϰ = 2ϰ + 12

6 X 3 = 18

6 X 5 = 30

30 + 12 = 42

18/42 = 3/7

Hmm.... My working seems correct. However, you guys' answers are 3/10 though... any ideas or advice?

P.S.
Total number of boys in club = 24
Total number of girls in club = 36

Hi there! Your answer is using \"no. of club members who did not take part in the competition\" as the denominator, whereas previous answer/s used \"total club members\" = 60.
Oh well...as with my previous post, I'm of the opinion that the denominator should be \"no. of club members who did not take part in the competition\" too.

cheers!


hi members, these are just for fun: what do these statements mean to you?

[1] The fraction of boys who did not take part in the competition is...
[2] Of those who did not take part in the competition, the fraction of boys is...

[3] I love you only
[4] Only I love you
[5] I only love you
[6] I love only you

[atutor2001]

ADoc:

hi members, these are just for fun: what do these statements mean to you?

[1] The fraction of boys who did not take part in the competition is...
[2] Of those who did not take part in the competition, the fraction of boys is...

[3] I love you only
[4] Only I love you
[5] I only love you
[6] I love only you

Hi ADoc

[1] means (No. of boys who did not take part)/(Total no. of boys)

[2] means (No. of boys who did not take part)/(Total no. of those who did not take part)
This is a good one. Becomes clearer if we rephrase as \"Out of those who did not take part in the competition, the fraction of boys is...\"

[3] The only person that \"I\" love is \"you\"
or The only reason that \"I\" am with \"you\" is love, nothing else
(not a good sentence - ambiguous)

[4] The only person that love \"you' is \"I\"

[5] The only reason that \"I\" am with \"you\" is \"love\", nothing else
or The only person that \"I\" love is \"you\"
(not a good sentence - ambiguous)

[6] The only person that \"I\" love is \"you\"

Am I right? :?

[ADoc]

atutor2001:

ADoc:

hi members, these are just for fun: what do these statements mean to you?

[1] The fraction of boys who did not take part in the competition is...
[2] Of those who did not take part in the competition, the fraction of boys is...

[3] I love you only
[4] Only I love you
[5] I only love you
[6] I love only you

Hi ADoc

[1] means (No. of boys who did not take part)/(Total no. of boys)

[2] means (No. of boys who did not take part)/(Total no. of those who did not take part)
This is a good one. Becomes clearer if we rephrase as \"Out of those who did not take part in the competition, the fraction of boys is...\"

[3] The only person that \"I\" love is \"you\"
or The only reason that \"I\" am with \"you\" is love, nothing else
(not a good sentence - ambiguous)

[4] The only person that love \"you' is \"I\"

[5] The only reason that \"I\" am with \"you\" is \"love\", nothing else
or The only person that \"I\" love is \"you\"
(not a good sentence - ambiguous)

[6] The only person that \"I\" love is \"you\"

Am I right? :?

haha! cheers atutor2001!
I think you are right or at least you have made inferences regarding the placement of the word \"only\" using a \"well-accepted\" norm (if I correctly recall my primary english teacher's comments 2 decades ago).

The norm (after almost 200 yrs of debate!) for using the word \"only\" is to place it before the word/s or phrases one is trying to modify. In casual prose, we can rely on various emphases as we speak to convey our intended meaning, but there isn't anything, except placements, to rely on in writing.

Anyway, the examples are meant to illustrate that certain degree of ambiguity is always present (& tolerated, & even purposefully intended sometimes) in the english language or any other languages. That's why math is the only universal language! haha!

Hope you had fun going through the sentences.
cheers! :celebrate:

[iFruit]

pixiedust:

Please help me with this P5 question.

Ratio not covered yet so prefer solution without using ratio. Thanks


Nancy has 3 times as many buttons as Mary.
Every day, Mary uses 5 buttons and Nancy uses 4 buttons.
When Mary has finished using all her buttons, Nancy has 88 buttons left.
(1) How many days does Mary take to use all her buttons ?
(2) How many buttons are there altogether at first ?

Let Mary = 5u
Then Nancy = 15u

No. of days for Mary to exhaust her buttons = u

Nancy:
15u - 4u = 88---> u = 8 = no. of days

Total buttons = 20u = 160

HTH.

[pixiedust]

Thank you iFruit. You made it look so simple !

The solution is considered algebra method ?