Q&A - P5 Math

[sushi88]

Hi, pls help on this question.

Miss Phua saved some 20-cent coins and 50-cent coins in the ratio of 3:4 in a box. She then decided to replace 1/3 of the 20-cent coins with the same number of 50-cent coins.The value of the amount she saved increased by $4.50. How much money was there in the box at first?
Thank you!

------------20-cents----50-cents
Before-------3u----------4u
After --------2u----------5u (because 1/3(3u)->u)
remove
1/3 20ct
and add
same number of 50 cents

50u-20u->450
30u->450
u->15
Money in box at first : 3(15)(0.20)+4(15)(0.50) = 9+30 = $39

[gem]

Hi all, need help for this question.

David took out all the coins in his piggy bank. They were made up of only twenty and fifty-cent coins. There were 12 fifty-cent coins more than twenty-cent coins. The total value of the fifty-cent coins was $21 more than the total value of the twenty cent coins. Find

a) the number of fifty-cent coins in David's piggy bank
b) the total value of the coins David had.

Can anyone help to draw the model for this question and explain your answers. It seems confusing to me.

Thanks.

[Ender]

We will compare the difference in value if they are the same quantity. So we take away 12 coins of 50c, value at $6, to make the quantity the same.
Now with same number of coins each, difference in value = 21-6= $15

Difference of one 50c & one 20c is $0.30

Number of 20c coins = 15/0.3 = 50
A) number of 50c coins = 50+12= 62 #

B) value of 20c = 50 x 0.2 = $10
Value of 50c = 62 x 0.5 = $31
Total value = $10 + $31 = $41##

[numeric]

Hi all, need help for this question.

David took out all the coins in his piggy bank. They were made up of only twenty and fifty-cent coins. There were 12 fifty-cent coins more than twenty-cent coins. The total value of the fifty-cent coins was $21 more than the total value of the twenty cent coins. Find

a) the number of fifty-cent coins in David's piggy bank
b) the total value of the coins David had.

Can anyone help to draw the model for this question and explain your answers. It seems confusing to me.

Thanks.

[Funz]

Moderator's Note: Question converted to AskQ. For all academic questions, please use our AskQ platform which is specifically intended for this purpose. Thank you.

[macaron12]

Algebra. heard from a mom that her child was taught in school by a relief teacher. She used it in Psle & passed with flying colors.

[chloecube]

Moderator's Note: Question converted to AskQ. For all academic questions, please use our AskQ platform which is specifically intended for this purpose. Thank you.

[BigDevil]

Hi chloecube, questions should be posted on the AskQ platform now,
You can access it here: https://www.kiasuparents.com/kiasu/askq/

[BigDevil]

need help on this.

3 boys, Adrian, bobby and calvin learnt to make some cookies.
they made an average of 138 cookies
Adrian and bobby made an average of 136 cookies, bobby and calvin made and average of 125 cookies. How many cookie did each of the boy made?

I forgotten how to do average already

Avg (A, B, C) -> 138
Total (A, B, C) -> 138 x 3 = 414

Avg (A, B) -> 136
Total (A, B) -> 136 x 2 = 272

C made (414 - 272) = 142 cookies

Avg (B, C) -> 125
Total (B, C) -> 125 x 2 = 250

B made (250 - 142) = 108 cookies

A made (272 - 108) = 164 cookies

[chloecube]

tks!!!