Q&A - PSLE Math

[MathIzzzFun]

lee tong fong:

Thanks for your solutions.


For question 6, I would like to know how do you work out the maximum number of group is 21.

For question 3, is this possible to work out the solution using the (Number of units X Value of units)

Find the largest common factor of 84 and 231 which is 21.

cheers.

[S6169]

PapayaDad:

lee tong fong:

Hi, can anyone help me with another question


(3) To make a fruit cake, Mrs Lim used 90% strawberry and 10% mango.
The cost of the mangoes was 1.5 times that of the strawberries.
She spent $6.30 in all for the strawberries and mangoes
How much more would it cost her if she uses 40% strawbeey and 60% mango?

Thanks you again

The cost of the mangoes was 1.5 times that of the strawberries.
interms of cost
1m=1.5s
10m=15s
90s : 15s
6s:1s
7s = 630
s = 90
m = 135

4s=360
6m=810
total=1170

1170 - 630 = 540

Sorry, put S=90, m=135 back to the Q,
9s+m=90*9+135=945 not 630, something wrong?

if you use:
90s : 15s
105s=630
s=6
m=9
then 40s+60m=780
difference 780-630=150

:?

[MathIzzzFun]

lee tong fong:

Hi, can anyone help me with another question


(3) To make a fruit cake, Mrs Lim used 90% strawberry and 10% mango.
The cost of the mangoes was 1.5 times that of the strawberries.
She spent $6.30 in all for the strawberries and mangoes
How much more would it cost her if she uses 40% strawbeey and 60% mango?

Thanks you again

Fruit cake --> 10 units --> 9 units of strawberries + 1 unit of Mangoes

Cost of mangoes was 1.5 times cost of strawberries
--> cost of 1 unit of mangoes was 3/2 times cost of 9 units of strawberries
...note that the statement does not mean that the cost of 1 mango is 1.5 times the cost of 1 strawberry.

Cost of 1 unit of mangoes = 3/5 x $6.30 = $3.78
Cost of 9 units of strawberries = $6.30 - $3.78 = $2.52
Cost of 1 unit of strawberries = $ 2.52 / 9 = $0.28

IF she uses 40% strawberries and 60% mangoes, then cost of the fruit cake will be
--> cost of 4 units of strawberries + cost of 6 units of mangoes
= 4 x $0.28 +6 x $3.78
= $ 23.80

Additional cost --> $23.80 - $6.30 = $17.50



cheers.

[Chalupa]

I need a help to solve this problem. A fruit seller had 600 apples & oranges altogether. After he sold 1/5 of his apples and bought another 60 oranges, the number of oranges was 2/5 the number of apples. How many more apples than oranges were there at first.( Ans.400) .Thanks in advance. :thankyou: :?:

[Chalupa]

Town A and Town B are 375km apart.Wen set off from Town A towards Town B at 1400 at a constant speed of 60km/h.1h later,Nelly set off from Town B towards Town At a constant speed of 80km/h.At what time did the two girls meet on the road? :thankyou:

[MathIzzzFun]

Chalupa:

I need a help to solve this problem. A fruit seller had 600 apples & oranges altogether. After he sold 1/5 of his apples and bought another 60 oranges, the number of oranges was 2/5 the number of apples. How many more apples than oranges were there at first.( Ans.400) .Thanks in advance. :thankyou: :?:

Please do not start a new thread.. post your question at the \"Q&A PSLE thread\"
- http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=280
--> go to the last post in the thread
--> click 'post reply\" and post your question.

--------------------------------------------------------
At first, number of apples --> 25 units
In the end,
Number of apples --> 20 units
Number of oranges --> 8 units
At first, number of oranges --> 8 units - 60

Total number of apples and oranges, at first --> 33 units - 60
33 units - 60 --> 600
1 unit --> 20

At first,
number of apples --> 25 x 20 = 500
number of oranges --> 8 x 20 - 60 = 100
500 - 100 = 400
at first, there were 400 more apples than oranges

cheers.

[MathIzzzFun]

Chalupa:

Town A and Town B are 375km apart.Wen set off from Town A towards Town B at 1400 at a constant speed of 60km/h.1h later,Nelly set off from Town B towards Town At a constant speed of 80km/h.At what time did the two girls meet on the road? :thankyou:

1h later at 15:00, the distance between Wen and Nelly
= 375 km - 60 km
= 315 km

In 1h,
total distance travelled by Wen and Nelly = 60 km + 80 km = 140 km
--> the distance (gap) between them reduces by 140 km in 1 hour

Time taken for the distance to reduce to zero --> 315 / 140 = 2.25h = 2h 15min

15:00 + 2h 15 min --> 17:15
they met at 17:15

cheers.

[Chalupa]

Thanks for the solution, but I don’t know how the no. Of apples are 25 units. Can you Please explain.

[PapayaDad]

after he sold 1/5 of his apples…

normally we will start with apple = 5u
sold 1/5 left 4u…

then… the number of oranges was 2/5 the number of apples…
aiya… 2/5 of 4u how ar?

so better go back and make apple = 25u (so i can divide it by 5 twice)
sold 1/5 left 20u
2/5 of 20u = 8u…

[ozora]

http://i40.tinypic.com/4rvu3k.jpg\">

wonder is the answer 65 or 75?