Q&A - P5 Math

[S-H]

MathIzzzFun:

S-H:

Hi please help me with this question, thanks!


1) Felicia wants to save some money to buy a notebook. She decided to do household chores for her mother in exchange for extra allowance. Her mother will give her $1 for the 1st week of work, $2 for the 2nd week of work, $4 for the 3rd week of work and so on. How many weeks will it take Felicia to make $2047?

...a geometric series .. is this from school worksheet ? for p5/p6, use guess and check

Total amount earned:

end of week 1 --> 1 = 2^1 -1
end of week 2 --> 1+2 =3 = 2x2-1 = 2^2 -1
end of week 3 --> 1+2+4=7 = 2x2x2 -1 = 2^3 -1
using calculator, you will arrive at
end of week 11 --> 2047 = 2^11 -1

cheers.

It's from sch worksheet (For P5). I used guess & check and it arrived at week 23 (a long list of guess & check), but yours is week 11, may I know why?Thank you.

[MathIzzzFun]

S-H:

MathIzzzFun:

[quote=\"S-H\"]Hi please help me with this question, thanks!


1) Felicia wants to save some money to buy a notebook. She decided to do household chores for her mother in exchange for extra allowance. Her mother will give her $1 for the 1st week of work, $2 for the 2nd week of work, $4 for the 3rd week of work and so on. How many weeks will it take Felicia to make $2047?

...a geometric series .. is this from school worksheet ? for p5/p6, use guess and check

Total amount earned:

end of week 1 --> 1 = 2^1 -1
end of week 2 --> 1+2 =3 = 2x2-1 = 2^2 -1
end of week 3 --> 1+2+4=7 = 2x2x2 -1 = 2^3 -1
using calculator, you will arrive at
end of week 11 --> 2047 = 2^11 -1

cheers.

It's from sch worksheet (For P5). I used guess & check and it arrived at week 23 (a long list of guess & check), but yours is week 11, may I know why?Thank you.[/quote]http://i33.tinypic.com/125p8ya.png\">

cheers.

[carol73]

hi

please help

Max and Tim had a total of 504 stickers, Max gave 1/8 of his stickers to Tim. Tim then gave 1/5 of the total stickers he had to Max. In the end, each of them had the same number of stickers. How many stickers did each of them have at first

this is what I did, stuck half way
no of stickers each of them had in the end 504/2 - 252

working backwards
Tim = 4P
Max = 3P

4p = 252 stickers
1p = 252/4 = 63 stickers
3p = 3*63 = 189
not sure how to continue after this

[MathIzzzFun]

carol73:

hi

please help

Max and Tim had a total of 504 stickers, Max gave 1/8 of his stickers to Tim. Tim then gave 1/5 of the total stickers he had to Max. In the end, each of them had the same number of stickers. How many stickers did each of them have at first

this is what I did, stuck half way
no of stickers each of them had in the end 504/2 - 252

working backwards
Tim = 4P
Max = 3P

4p = 252 stickers
1p = 252/4 = 63 stickers
3p = 3*63 = 189
not sure how to continue after this

http://i34.tinypic.com/2d0x349.png\">

cheers.

[carol73]

THANKS

[S-H]

Hi MathIzzzFun, sorry to borther you again. May I know how you get end of week 4, she received $8, end of week 5 -$16, end of week 6 - $32 and so on… Thanks!

[MathIzzzFun]

S-H:

Hi MathIzzzFun, sorry to borther you again. May I know how you get end of week 4, she received $8, end of week 5 -$16, end of week 6 - $32 and so on.... Thanks!

I assume that the amount given by the mother is doubled every week
week 1's allowance --> $1 ... total allowance --> $1
week 2's allowance --> 2 x $1 = $2 ... total allowance --> $1+$2 = $3
week 3's allowance --> 2 x $2 = $4 ... total allowance --> $1+$2 +$4 = $7
week 4's allowance --> 2 x $4 = $8 ... total allowance --> $1+$2 +$4 + $8 = $15
.... and so forth

The question can also be interpreted as:
week 1 --> $1
week 2 --> $2
week 3 --> $4
week 4 --> $7
week 5 --> $11 .. and so forth .. this series is basically a triangular number series and to find the sum to 2047 will require the student to add to week 23 - I feel that this is too lengthy, which is why I had presumed that the question intended that the allowance be doubled every week. You may want to check with the teacher on this.. to make the question clearer, an additional sentence should be added :
either --> ..$4 for the 3rd week of work and $8 for the 4th week and so on...

or --> $4 for the 3rd week of work and $7 for the 4th week and so on..


cheers.

[chloecube]

Mrs Bala bought some paper folders for her pupils. 2/7 of them were yellow, 4/7 were pink and the rest blue. she gave 2/3 of the yellow paper folders to the boys and 1/3 of the pink paper folders to the girls. she had 208 paper folders left.

a) how many paper folders did she gave to the boys?
b) Mrs Bala paid $0.90 for each paper folder. how much did she pay for all paper folders?

[tianzhu]

chloecube:

Mrs Bala bought some paper folders for her pupils. 2/7 of them were yellow, 4/7 were pink and the rest blue. she gave 2/3 of the yellow paper folders to the boys and 1/3 of the pink paper folders to the girls. she had 208 paper folders left.

a) how many paper folders did she gave to the boys?
b) Mrs Bala paid $0.90 for each paper folder. how much did she pay for all paper folders?

Hi

Yellow ------ 6 units
Pink ------ 12 units
Blue ------- 3 units

Yellow@boys ------- 4 units
Pink@girls -------- 4 units

Paper folders left ------- 13 units
13 units ------- 298
1unit -------- 16

Paper folders given to boys -------- 16*4 ------- 64

Total number of folders ------ 21* 16 ------- 336
Total cost -------- 336*0.9 -------- 302.40

Best wishes

[MathIzzzFun]

chloecube:

Mrs Bala bought some paper folders for her pupils. 2/7 of them were yellow, 4/7 were pink and the rest blue. she gave 2/3 of the yellow paper folders to the boys and 1/3 of the pink paper folders to the girls. she had 208 paper folders left.

a) how many paper folders did she gave to the boys?
b) Mrs Bala paid $0.90 for each paper folder. how much did she pay for all paper folders?

Total number of paper folders --> 21 units
Yellow folders --> 6 units
Pink folders --> 12 units
blue folders --> 3 units

Yellow folders given to boys --> 2/3 x 6 units = 4 units
Pink folders given to girls --> 1/3 x 12 units = 4 units
Folders left --> 21 units - 4 units - 4 units = 13 units

13 units --> 208, 1 unit --> 16

Yellow folders given to boys --> 4 x 16 = 64

Total number of folders --> 21 x 16 = 336
Total amount paid for the folders --> 336 x $0.90 = $302.40

cheers.