Q&A - P4 Math

[tianzhu]

BigDevil:

Like CNS, I'm quite confused.

44 cars, 0 bicycle ----> 44 * 4 = 176 wheels
43 cars, 1 bicycle ----> 43 * 4 + 1 * 2 = 174 wheels

So why do you say that \"for every increase in 1 bicycle, the difference in the number of wheels drops by 6\"? Isn't it 176 - 174 = 2 wheels??

Hi

There are 44 cars and bicycles. There are 128 more car wheels than bicycles. How many cars and bicycles are there?

43 cars ------ (43*4) ----- 172
1 bicycle ----- (1*2) ------ 2

Difference in number of wheels ------ (172-2) -------170

176 – 170 ------6

Please compare with this question.

There are 44 cars and bicycles. There are 128 wheels altogether. How many cars and bicycles are there?

In this case the difference is 2.

Best wishes

[KSP]

44 cars & bikes

128 more car wheels than bike

128 / 4 = 32cars
44 - 32 = 12 cars & bikes

Divide 12 into cars & bikes with both having same no. wheels

8 bikes x 2 = 16 wheels
4 cars x 4 = 16 wheels

Therefore there are 8 bikes.

Number of cars = 4 + (128/4) = 4 + 32 = 36

[sokk]

Hi,


I've a question that goes like this-

Each digit can be used only once.
Arrange the digits 2,4,7,8 and 9 in these boxes so as to get the largest and smallest possible products.

Largest product. : [ ][ ][ ] x [ ][ ] =
Smallest product : [ ][ ][ ] x [ ][ ] =

The answer is
872 x 94 = 81968 ( for the largest product)
489 x 27 = 13203. (for the smallest product)

The answer said that the method is by \"guess and check\". So wouldn't the students have a number of combinations to try out ?
Is there a more direct method in doing this kind of question rather than by guess and check ?


Thanks for helping me answer my question

[chloecube]

hi,


need help on this.thks

James has twice as much money as Alex. After Alex spent $50, James had thrice as much as Alex. how much money did James have than Alex at first.

[Nebbermind]

alan000:

http://i42.tinypic.com/69p8jk.gif\">

cmm:

Sue has more than 50 hairpins.

If she puts them in packets of 7, she has 5 hairpins left.
If she puts them in packets of 9, she has 6 hairpins left.
How many hairpins does Sue have?

Dear cmm,

Hope this helps.

Are there any other method of solving this qn? Like using models?

[MathIzzzFun]

chloecube:

hi,


need help on this.thks

James has twice as much money as Alex. After Alex spent $50, James had thrice as much as Alex. how much money did James have than Alex at first.

Hi

http://www.flickr.com/photos/62167097@N02/6773560540/in/photostream

cheers.

[chloecube]

MathIzzzFun:

chloecube:

hi,


need help on this.thks

James has twice as much money as Alex. After Alex spent $50, James had thrice as much as Alex. how much money did James have than Alex at first.

Hi

http://i41.tinypic.com/jfxkle.jpg\">

cheers.

thks MathIzzzFun,
but i do not quite understand why you only drew 2 units in the 2nd model since James has thrice as much as Alex after the $50 spent.
shldnt it be 3 units instead?

Thks

[chloecube]

chloecube:

MathIzzzFun:

[quote=\"chloecube\"]hi,


need help on this.thks

James has twice as much money as Alex. After Alex spent $50, James had thrice as much as Alex. how much money did James have than Alex at first.

Hi

http://i41.tinypic.com/jfxkle.jpg\">

cheers.

thks MathIzzzFun,
but i do not quite understand why you only drew 2 units in the 2nd model since James has thrice as much as Alex after the $50 spent.
shldnt it be 3 units instead?

Thks[/quote] :oops: okok, i think i got it, thks!!!

[HAPPYH]

MathIzzzFun:

chloecube:

hi,


need help on this.thks

James has twice as much money as Alex. After Alex spent $50, James had thrice as much as Alex. how much money did James have than Alex at first.

Hi

http://i41.tinypic.com/jfxkle.jpg\">

cheers.

Nice explanation. Thank you so much.

[chloecube]

Thank you all for the help rendered, esp to tian zhu and mathIzzzFun!

i am going :siao: with DS's heuristic math, but i have the kick if i managed to solve them, and :faint: if i am stuck.

Thks everyone