Q&A - P5 Math

[lego]

PapayaDad:

Total=8u


B+C=7u
A=u

B=6u
A+C=2u

B-A=6u-u=5u=30
u=6
Total=8u=48

Thank you so much!

[Shimmer]

Hi


Can someone help me on these two question ?

1. Daniel has $160 more than Raja. If Daniel gives Raja 1/10 of his money, he will have 3 times as much money as Raja.
A) How much money does Raja have at first ?
B) Express Raja’s money as a fraction of Daniel’s money.

2. There were 240 people in a shopping centre. 3/5 of them were men. Some men then left the shopping centre. The number of men in the shopping centre was 4/7 of the remaining people. How many men left the shopping centre ?

[tianzhu]

Shimmer:

Hi

Can someone help me on these two question ?
1. Daniel has $160 more than Raja. If Daniel gives Raja 1/10 of his money, he will have 3 times as much money as Raja.
A) How much money does Raja have at first ?
B) Express Raja's money as a fraction of Daniel's money.

Hi

You may use MD or work with units.

Before
Daniel ------ 10 units + 160
Raja ------ 10 units

AfterDaniel ------ 9 units + 144
Raja ------ 11 units + 16

11 units + 16
(x3)
33 units + 48

33 units + 48 --------- 9 units + 144

24 units ------ 96
1 unit ------- 4

Raja ------ 10 units -------10*4 ------ 40

Daniel ------ 10 units + 160 ------- 200

Raja's money as a fraction of Daniel's money ------ 40/200 ------1/5

Best wishes

[tianzhu]

Shimmer:

Hi

2. There were 240 people in a shopping centre. 3/5 of them were men. Some men then left the shopping centre. The number of men in the shopping centre was 4/7 of the remaining people. How many men left the shopping centre ?

Hi

At first
men:women ------ 3:2 ------- (x3) ------- 9:6

In the end
men:women ------ 4:3 -------- (x2) ------- 8:6

The number of women before and after stays the same, so make the units for women the same.

15 units ------ 240

1 unit ------ 16

Number of men@left shopping centre ------16

Best wishes

[hazelwong]

Hi, can anyone help with this qn?

Mrs tan bought 42 apples. Each apple costs 75cents less than a pear. She spent the same amount of money on 12 pears. How much did Mrs Tan spend on buying the apples?

I managed to solve it only with algebra:
let X be price of pear
42 (X-0.75) = 12X
42X-31.50 = 12X
30X = 31.50
X = 1.05
price of apple 1.05- 0.75 = 0.3
42x0.3 = 12.60
Ans $12.60

Is using algebra ok?
Is there any other way e.g. model or units/parts?
thanks v much

[MathIzzzFun]

hazelwong:

Hi, can anyone help with this qn?

Mrs tan bought 42 apples. Each apple costs 75cents less than a pear. She spent the same amount of money on 12 pears. How much did Mrs Tan spend on buying the apples?

I managed to solve it only with algebra:
let X be price of pear
42 (X-0.75) = 12X
42X-31.50 = 12X
30X = 31.50
X = 1.05
price of apple 1.05- 0.75 = 0.3
42x0.3 = 12.60
Ans $12.60

Is using algebra ok?
Is there any other way e.g. model or units/parts?
thanks v much

cost of 42 apples = cost of 12 pears
cost of 1 apple = 12/42 cost of 1 pear = 2/7 cost of 1 pear
1 pear --> 7 units
1 apple --> 2 units

1 apple cost 75 cents less than 1 pear,
5 units --> 75 cents
1 unit --> 15 cents

cost of 1 apple --> 30 cents
cost of 42 apples --> 42 x $0.30 = $ 12.60

cheers.

[chloecube]

carol73:

hi


how do you determine that now is 3units
thanks

chloecube:

[quote=\"carol73\"]The Queen, prince and princess had 270 diamonds. After receiving 90 diamonds for her birthday, the Queen decided to give 1/2 of the diamonds to the prince, the prince than gave 2/5 of his diamonds to the princess.in the end the three of them had the same number of diamonds, how many diamonds did each of them have at first

270 + 90 = 360

now -
Queen - 3 units
Prince - 3 units
princess - 3 units

work backwards
before -
Queen - 6 units
Prince - 2 units
princess - 1 unit

9u - 360
1u - 40

so Queen - 240 - 90 = 150
Prince - 80
princess - 40

[/quote]hi,
i work backwards, starting with the Prince, he gave 2/5 to the princess, so he left 3units. and in the end they all have the same nos of unit.
so i take it as all of them have 3 units and i work slowly from there

[purple05]

All 150 seats at the back row of a concert hall are priced at 3/5 that of the other seats. There are 600 seats altogether, and when all the seats are sold, the amount collected is $2700. Find the price of each seat at the back row of the concert hall

[PapayaDad]

150 x 3/5 = 90


Number of other seats = 600-150=450

450+90=540

2700/540=5 (price of other seat)

back row = 3

check
450x5=2250
150x3= 450
Total = 2700…correct

[MathIzzzFun]

purple05:

All 150 seats at the back row of a concert hall are priced at 3/5 that of the other seats. There are 600 seats altogether, and when all the seats are sold, the amount collected is $2700. Find the price of each seat at the back row of the concert hall

using units approach...

price of normal seat --> 5 units
price of back row seat --> 3 units

Total collected --> (600-150) x 5 units + 150 x 3 units = 2700 units
2700 units --> $ 2700
1 unit --> $1

Price of normal seat --> $5
price of back row seat --> $3

cheers.