Q&A - P4 Math

[Jamesbond]

MathIzzzFun:

Jamesbond:

http://i46.tinypic.com/2573bds.jpg\">


The ans for ques (a) is 15 unit shapes...I donno to solve ques (b). Pl help me...............

Hi

pattern 1 --> 1 = 1x2 /2
pattern 2 --> 3 = 2x3 /2
pattern 3 --> 6 = 3x4 /2
pattern N = N x (N+1) /2 --> 1/2 x product of pattern number N and the next consecutive number
pattern 5 --> 5x6 /2 = 15

Total = 210
ie 1/2 x product of pattern number N and the next consecutive number = 210
or product of 2 consecutive numbers (N & N+1) = 420
.. use guess and check to find the number N --> the nearest square number = 400 = 20 x 20
20 x 21 = 420
N = 20
Pattern 20 has 210 shapes

cheers.

:thankyou: :salute: :salute:

[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:

[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.

[kiasuMay11]

MathIzzfun,

Can u explain a little regarding the area model? I cant really get it. Why there are 3 ‘W’?

[MathIzzzFun]

kiasuMay11:

MathIzzfun,

Can u explain a little regarding the area model? I cant really get it. Why there are 3 'W'?

Hi

W is the area representing total points for wrong answer.
Total points scored from correct answer (before deducting the points for wrong answer) is the blue area (68) + W.

The new rectangle comprising (W+X+W) is drawn to show how to calculate the number of wrong questions. This rectangle has an area equal to difference of the perfect score and the actual score --> 100-68= 32 and since the height of this rectangle is known, the number of wrong questions can thus be determined.

cheers.

[kiasuMay11]

Mathizzfun,

Thanks… quite tough to explain to my P4

[Jamesbond]

MathIzzzFun:

Jamesbond:

http://i49.tinypic.com/mhf3a9.jpg\">


pl help me solve this......

hi

http://i45.tinypic.com/15d03s6.png\">

cheers.

Fantastic method.....my salutations to u.... :salute:

[Jamesbond]

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.

Ur guidance is awesome I say...... :rahrah:

[Thein]

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:

http://i47.tinypic.com/1117ckh.jpg\">

[kiasuMay11]

Thein,

Where did the 5 of 35/5 come from?