Q&A - P4 Math

[kiasuMay11]

13 correct answer is right

[PiggyLalala]

Jamesbond:

Tan participated in a math quiz with 20 questions. For every correct answer, he was awarded 3 points. For every wrong answer, 2 points were deducted. If tan scored 25 points for the quiz, how many questions did tan answer correctly?


Pl help me solve this..... :yikes:

Assuming he has answered all the questions correctly.
total points = 20 X 3 = 60.
Scored 25 points= lost 60- 25 = 35 points.

For each wrong answer, he lost 3 + 2 = 5 points
Therefore 35/5 = 7 wrong answers
that is 20 - 7 = 13 correct answers

[PiggyLalala]

MathIzzzFun:

Jamesbond:

Tan participated in a math quiz with 20 questions. For every correct answer, he was awarded 3 points. For every wrong answer, 2 points were deducted. If tan scored 25 points for the quiz, how many questions did tan answer correctly?


Pl help me solve this..... :yikes:

Hi

here's a similar question.. using area model..

http://www.flickr.com/photos/62167097@N02/7319052572/in/photostream

cheers.

Hi MathIzzzfun,
I do not quite understand the area method. May I know what does the area X represent and why are there 2 area W? Thanks. Which other types of sums can be solved by these area method? thank you

[MathIzzzFun]

PiggyLalala:

Hi MathIzzzfun,
I do not quite understand the area method. May I know what does the area X represent and why are there 2 area W? Thanks. Which other types of sums can be solved by these area method? thank you

Hi

here's the area model solution for the posted question.. I have added interim models and explanation for how the final model is derived ..

http://i49.tinypic.com/2e5164z.png\">

I developed this approach (it is really the assumptive method using MD) because I find that some students are not able to use the Guess & Check for such questions, and got confused with the \"difference\" when using the assumptive method. Using the area model, determination of the difference is \"built in\".

This method basically made use of equal areas to calculate the required answers, and therefore the same can be applied to questions on averages, gap/difference question, speed etc.

cheers.

[Thein]

kiasuMay11:

Thein,

Where did the 5 of 35/5 come from?

5 is the difference from the first iteration and second iteration.

60 - 55 =5

35 is the difference from the first iteration and final answer...

60 - 25 = 35

hope it helps.

[PiggyLalala]

MathIzzzFun:

PiggyLalala:

Hi MathIzzzfun,
I do not quite understand the area method. May I know what does the area X represent and why are there 2 area W? Thanks. Which other types of sums can be solved by these area method? thank you

Hi

here's the area model solution for the posted question.. I have added interim models and explanation for how the final model is derived ..

http://i49.tinypic.com/2e5164z.png\">

I developed this approach (it is really the assumptive method using MD) because I find that some students are not able to use the Guess & Check for such questions, and got confused with the \"difference\" when using the assumptive method. Using the area model, determination of the difference is \"built in\".

This method basically made use of equal areas to calculate the required answers, and therefore the same can be applied to questions on averages, gap/difference question, speed etc.

cheers.

:thankyou: for the step by step explanation to the area method.
A good method.

[chloecube]

12 times of a mystery number is 11583 more than 3/10 of the same mystery number. find the mystery number.


3 times of a mystery number is 1736 more than 2/11 of the same mystery number. what is the mystery number.

[tianzhu]

chloecube:

12 times of a mystery number is 11583 more than 3/10 of the same mystery number. find the mystery number.


3 times of a mystery number is 1736 more than 2/11 of the same mystery number. what is the mystery number.

Hi

For P4 kids, a neat way is to use MD.

Mystery number ----- 10 units

Draw a long bar to show 120 units (12 times of a mystery number).

Draw 3 units to show 3/10 of the same mystery number.

120 – 3 ----- 117

117 units ------- 11583

1 unit ------ 99

The mystery number ------- 10 units -------- 990

I’ll leave it to you to work out Q2.

Start with the mystery number ----- 11 units.The answer is 616.

Best wishes

[chloecube]

got it, thks!

[Michell0328]

Hi,I have lot of question to solve, can you help me?? :scratchhead:

Q1)A piece of cloth was 4.5m long.2.35m of the cloth were used to sew a dress.How many metres of cloth were left??

Q2)Mrs Lee drove from school to her home which was 8.7km away.After driving 3.75km,she stopped at a supermarket along the way.How much further did she have to drive before she reached her home?

3)Sulin bought a skirt for $25.90 and a blouse for $19.50. She paid the cashier $50.How much change did she receive?