Q&A - P5 Math

[MathIzzzFun]

Chan09:

MathIzzzFun:

[quote=\"Chan09\"]Need some help:

1) a stack of bookmarks was shared among A,B and C. A received 3 more than 50% of the bookmarks. B received 5 more than half of the remaining bookmarks. After A and B had taken their share, C received 50% of the remainder and the last 3 bookmarks. What percentage of the stack of bookmarks did C receive?
Ans: 12%

Hi

work backwards.. eg by branching, model..

C received 50% of the remainder (after A & B had taken theirs) + 3 bookmarks --> 50% of the remainder is 3, so, C took 3 + 3 = 6

B received 5 more than 50% of the remainder after A had taken --> remainder is 5 less than 50% of remainder = 6 --> 50% of remainder = 6 + 5 = 11 , so remainder (after A taken) = 11 x 2 = 22

A took 50% + 3 --> 50% = 22 + 3 = 25, total number of bookmarks at first = 50

percentage of C's bookmarks = 6/50 x 100% = 12%

cheers.

[/quote]Hi

solutions using branching & model ..

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http://i41.tinypic.com/14mg96u.jpg\">

cheers.

[Chan09]

Chij ca2 2010

1) not sure if question had an error?
Bought mangoes and avocados for $86.50. A mango and an avocado cost $11 in all. He bought more mangoes than avocados and mangoes cost $42.50 more. How many avocados did he buy?
And: 4

If I take 42.50 + 2x = 86.50, x being the unit price of avocado it is $22 but then can’t seem to find the number of avocados?

[tianzhu]

Hi Moderator


Please help to delete post.

Best wishes

[MathIzzzFun]

Chan09:

Chij ca2 2010

1) not sure if question had an error?
Bought mangoes and avocados for $86.50. A mango and an avocado cost $11 in all. He bought more mangoes than avocados and mangoes cost $42.50 more. How many avocados did he buy?
And: 4

If I take 42.50 + 2x = 86.50, x being the unit price of avocado it is $22 but then can't seem to find the number of avocados?

Hi

question is not properly set... given choices 1) 2, 2) 4, 3) 5, 4)9. Both 2) and 3) ie 4 avocados and 5 avocados are right answers.

From the given information, we would arrive at
$ 64.50 paid for mangoes,
$ 22.00 paid for avocados.
Since 1 mango + 1 avocado = $11 --> total cost of equal number of mangoes and avocados will be a multiple of 11

Thus, we have (amount shown in red for mangoes and in green for avocado)
3 avocados + 3 mangoes --> $22 + $11 + $53.50
4 avocados + 4 mangoes --> $22 + $22 + $42.50
5 avocados + 5 mangoes--> $22 + $33 + $31.50
6 avocados + 6 mangoes --> $22 + $44 + $20.50
7 avocados + 7 mangoes --> $22 + $55 + $9.50

possible number of avocados --> 3, 4, 5, 6, 7
so, both answers 2) & 3) are correct.

cheers.

[shyaning]

Hi,


Can someon help me with this qn please?

5 similar files cost $3 more than 3 similar pens. Mrs Lee purchased 3 files and 6 pens for $17.40. What was the cost f each file?

Thanks a billion

[MathIzzzFun]

shyaning:

Hi,


Can someon help me with this qn please?

5 similar files cost $3 more than 3 similar pens. Mrs Lee purchased 3 files and 6 pens for $17.40. What was the cost f each file?

Thanks a billion

Hi
5 files = 3 pens + $3 --> 10 files = $6 + 6 pens --> 6 pens = 10 files - $6

3 files + 6 pens --> $ 17.40
3 files + 10 files - $ 6 --> $ 17.40
13 files --> $ 23.40
1 file = $1.80

cheers.

[shyaning]

MathIzzzfun,


Thanks alot for the solution…

Shyaning

[Chan09]

Need some help.

G and J shared the cost of dinner in the ratio 2:3. G used half his money to pay his share. After paying, J had $84 left. The ratio of the amt that G had at first to the amt of money J had at first was 3:4. How much was the total bill for dinner?
Ans: $180

My working was:
G : J
at first 3u: 4u
Cost -2p: -3p
End. 3/2u: ? ($84)

Hence 3G- 3/2u = 3/2 u= 2p
Solve for p and do subsitution but can’t get the answer.

[serenasgreenhouse]

G : J

3 : 4
12: 16 (Use equivalent ratio concept)

G spent 1/2 of 12 units i.e. 6 units

Amount G spent : Amount J spent
2 : 3
6 : 9

16 - 9 = 7
(Explanation: J has 16 units at first and spends 9 units. Therefore he has 7 units left)

7 units - 84
1 unit - 12
15 units - 180 (12 x 15)
(Note: Dash should be arrow sign. Not familiar with KSP so not sure how to find the arrow symbol )

[small]

[quote]G and J shared the cost of dinner in the ratio 2:3. G used half his money to pay his share. After paying, J had $84 left. The ratio of the amt that G had at first to the amt of money J had at first was 3:4. How much was the total bill for dinner?[/quote]
HTH...

At first the amt of money G to J was 3:4

At first
G : J
3 : 4
12U : 16U

G and J shared the cost of dinner in the ratio 2:3 and G used half his money to pay his share which means :

cost of dinner
G : J
2P: 3P

For G:
12U-2P = 6U
2P = 6U
1P = 3U
3P = 9U

For J:
16U - 9U = $84
7U = $84
1U = $12

Cost of dinner = 5P or 15U
15 x $12 = $180

The total bill for dinner was $180