120 students weigh an average of 60kg. each boy weighs 63kg. each girl weighs 59kg. whats the difference. between the number of boys and the number of girls?

thk u

Can show ans?

Here's the answer. Similar working. Try it ☺

thk u all.

There are many levels of the questions that can use assumption to solve, we may choose the appropriate one depends on the student's level. One of the difficult question is here.. I think😂, my method may not a good one but the question is challenge Let's try.

i guess for this one i would rather go for guess n check. wht u think

coz there are 3 numbers here $5 $10 and $50

yup guess n check

thk u everyone

just a qsn in assumption method does it matter if we assume a lower fig thn the larger one? for eg $2 and $5... we assume all $2 or assume all $5

Does not matter. Both will get you the same answer.

thk u

But if the question ask for no of $2..... Start off by assuming all $5.

yes tts the one

ie, If the Q ask for "A", assume all are "B". Will save you some steps.

But even if you all are "A"... You will get the same ans, just that u use more steps (and time).

ok so if qsn ask A assume all B if qsn ask B assume all A. thk you so much one and all

Yup

Wahidah Khan, This is a Question which my friend (alr in this thread....) and I came up with. Invovles the use f assumption method, but brings it to a slightly higher level probably? Taken from our Mock Paper

thk u

Here are the solutions to the question.

how u solve it Rye

wow tough

Straight As... sounds good 😄

.... maybe I should use X and Y instead....

Week 1 $10. Week 2 $10 + 4 Week 3 10+(4x2) note that we always multiply 4 with a number that is minus 1 from the week. Week 4 10 + (4x3) ... So 154-10=144. 144÷4=36 36+1=37 So it takes 37weeks. To check: Week 37 10+(4×36)=10+144 =154. Hope this is correct..:)

Thank you for the suggested answers. Using Trial & error method, i add week 1-7 savings, 10+14+18+22+26+30+34=$154 Is there a formula or shorter method to solve?

This is number pattern. Once u are familiar with this pattern, +4, +4, +4, Just find what number +4. In this case, 10 = 6 + 4 So the formulae is 6 +4n, Where n = number of weeks

Raymond Ng. What's wrong with my working?? Thanks

Thank you Raymond. Its a P3 qn. Kids yer to learn algebra.

Another method which I like to use. Since it's an increase of 4 throughout. Wk 1 - 1 X 4 + 6 = 10 Wk 2 - 2 X 4 + 6 = 14 Wk 3 - 3 X 4 + 6 = 18 So 154 = __ X 4 + 6

p3 Parents, do join us at https://www.facebook.com/groups/therealparents2006/ You may be required to verify that u are a real parent.

Raymond ng is correct. The question wants accumulated total. If you just add $4 that is just that amount saved for that week. Not inclusive of the amounts of the previous week.

Hi Jane, the answer is 7 weeks or 37 weeks?

Oops.. seems like my answer is wrong! Didn't take into account that that it's cumulative.

Izam Marwasi, your answer would have been perfectly fine if the question is "In which week would she have saved $154" But now, the question is apparently asking how many weeks have passed before her piggybank has accumulated $154. Hope that helps ☺

Thanks..

2 × 7 × 11 isn't algebra ☺ I merely used n coz someone asked if there is a formula. Think of it this way: The accumulated amount saved are: 10, 24, 42, ... 10 = 2 × 1 × 5 24 = 2 × 2 × 6 42 = 2 × 3 × 7 ... See the pattern?

In any case, if you want to calculate in which week she would save $154, an alternative method is (154 - 6) ÷ 4 = 37

Thank you Raymond. I was told the only way is to keep adding till I get $154 for P3 lvl. Sch won't gv them a big figure to work with.

Sure. Keep adding is fine so long as the number isn't too big e.g. 960 ☺

😰😰😰😰

Be it P3/4/5/6 or Sec1/2/3/4/5 or JC1/2, When it comes to number patterns, my advice to students is the same: get the general nth term, then you can get ANY term ☺

7 weeks. Wk 1- $10 Wk 2- $14 Wk 3- $18..... Keeping adding till 7 weeks you got tt amt. $10+14+18+22+26+30+34=

Thanks...

Thank you yueh Mei for help 👍