Q&A - P5 Math

[ChewingPencilLine]

Jamesbond:

ChewingPencilLine:

[quote]2. Mary spent $270 on a necklace. She spent 1/7 of her money on a dress. She then had 3/8 of her money left. How much money did she have at first?

It might be good to draw the model for this question (if you have trouble visualizing) although I am not going to provide one in the following solution.

After spending $270, Mary has some money left. Let us call that the remainder.
She then spent 1/7 of the remainder on a dress.
Thereafter, she is left with 6/7 of the remainder.

Therefore, 6/7 of remainder = 3/8 of her total money
For reasonable comparison, you need the unit size to be the same!

As such, find the lowest common multiple of 6 and 3. Then make the numerator the same (same amount represented by the same number of units -> units are of the same size), i.e.

6/7 of remainder = 6/16 of her total money

As such, her total money can be represented using 16 units. The remainder is then represented using 7 units.

The money spent on the necklace is hence represented by
16 - 7 = 9 units

9 units = $270
1 unit = $270 / 9 = $30
16 units = $30 x 16 = $480

Hi, Sorry to interrupt..She only spent 1/7 of the money on the dress and not the remainder. So the steps are

1/7=8/56
3/8=21/56
21/56+8/56=29/56
56-29=27
270/27=10
56*10=560
Correct me if I am wrong.[/quote]You are quite right in your workings and correction, thank you! Can't believe I actually misread the question! My apologies and thank you!

[chloecube]

Jim and Andy had 522 cards. Jim gave 4/7 of his cards to Andy. Andy then gave 2/5 of the total number of cards he had to Jim. In the end, each of them had the same Nos of card. How many cards did each of them have at first?

[Jamesbond]

http://i48.tinypic.com/24biv4n.jpg\">


Pl help.

[ChewingPencilLine]

chloecube:

Jim and Andy had 522 cards. Jim gave 4/7 of his cards to Andy. Andy then gave 2/5 of the total number of cards he had to Jim. In the end, each of them had the same Nos of card. How many cards did each of them have at first?

Total number of cards does not change so Jim and Andy each have
522 / 2 = 261 cards at the end.

Working backwards...
This is after Andy gave away 2/5 of his total number of cards to Jim, which means he was left with 1 - 2/5 = 3/5 of his cards.

Therefore, before giving away some cards to Jim, Andy had
261 / 3 * 5 = 435 cards
and Jim had 522 - 435 = 87 cards.

This is after Jim gave 4/7 of his cards to Andy.
Similarly, 1 - 4/7 = 3/7

Therefore, before giving away some cards to Andy, Jim had
87 / 3 * 7 = 203 cards

Hence, the final answer is as follows:

Jim had 203 cards at first while Andy had 522 - 203 = 319 cards at first.

[ChewingPencilLine]

Jamesbond:

http://i48.tinypic.com/24biv4n.jpg\">


Pl help.

Unshaded area = half the area of a square + half the area of 3 squares
(the bottom row of 3 squares form a rectangle which is half shaded)

Since 1 square is 16 x 16 = 256 cm square,
The total unshaded area is 1/2 x 256 + 1/2 x 3 x 256 = 2 x 256 = 512 cm square.

[chloecube]

I see, thks

[Oracle]

Thanks Tianzhu but i just need to understand why Wee Teck is given 3 units because the question says Robert paid 1/3 of the amount paid by Henry AND Wee Teck. By using 3 units to represent Wee Teck, we would be assuming that both Wee Teck and Henry paid equal amount which might mot be the case.


Your thoughts?

[tianzhu]

Oracle:

Thanks Tianzhu but i just need to understand why Wee Teck is given 3 units because the question says Robert paid 1/3 of the amount paid by Henry AND Wee Teck. By using 3 units to represent Wee Teck, we would be assuming that both Wee Teck and Henry paid equal amount which might mot be the case.


Your thoughts?

Hi

Please read your PM.

Best wishes

[carol73]

hi


1)An egg-seller had some chicken eggs and duck eggs. He had 96 more chicken eggs than duck eggs. After he had sold 3/4 of the chicken eggs and 2/3 of the duck eggs, he found that he had 150 eggs left. Find the total number of eggs he had at first?

2)Miss Lee baked 24 more chocolate muffins than banana muffins. After she gave away 1/6 of the chocolate muffins and 3/8 of the banana muffins, she was left with 35 more chocolate muffins than banana muffins. How many chocolate muffins did she bake at first?

[carol73]

hi

can you explain this step

Therefore, before giving away some cards to Jim, Andy had
261 / 3 * 5 = 435 cards
and Jim had 522 - 435 = 87 cards.

why 261 / 3 * 5?

ChewingPencilLine:

chloecube:

Jim and Andy had 522 cards. Jim gave 4/7 of his cards to Andy. Andy then gave 2/5 of the total number of cards he had to Jim. In the end, each of them had the same Nos of card. How many cards did each of them have at first?

Total number of cards does not change so Jim and Andy each have
522 / 2 = 261 cards at the end.

Working backwards...
This is after Andy gave away 2/5 of his total number of cards to Jim, which means he was left with 1 - 2/5 = 3/5 of his cards.

Therefore, before giving away some cards to Jim, Andy had
261 / 3 * 5 = 435 cards
and Jim had 522 - 435 = 87 cards.

This is after Jim gave 4/7 of his cards to Andy.
Similarly, 1 - 4/7 = 3/7

Therefore, before giving away some cards to Andy, Jim had
87 / 3 * 7 = 203 cards

Hence, the final answer is as follows:

Jim had 203 cards at first while Andy had 522 - 203 = 319 cards at first.