Q&A - P5 Math

[lotto]

ozora:

verykiasumummy:

[quote=\"ozora\"]Need guide in this question only: The number of basketballs was 3/5 of the number of footballs. In jan , 1/3 of the basketball and 1/3 of the football were sold. In feb,4 basketball n 4 footballs were sold. The number of basketballs left was 1/2 of the number of footballs. How many basketballs were there at first?


Thanks

just trying to help.

The number of basketballs was 3/5 of the number of footballs.

means ratio of basket:foot is 3:5.

In jan , 1/3 of the basketball and 1/3 of the football were sold.

so ratio has to be multiplied by 3.
basket : foot
9 : 15
-3u -5u
---------------
6 : 10

In feb,4 basketball n 4 footballs were sold.

basket : foot
6 : 10
-4 -4
---------------
1 : 2

since 6u-2u=4u, and 10u-2u=8u, which is exactly half, therefore

2u --> 4
1u --> 2
at first there were 9u basketball, so
9u --> 18

ans is 18.

think there is a mistake. the subtraction of basket is 6u-1u =5u .
therefore cannot be half.[/quote]
@ozora:
try to use units and parts to continue from the table given! u can find that 2u = 4

@verykiasumummy:
your steps to get '2u = 4' is not so reliable. if the number is not so nice, u might not be able to guess the '2u'
Nice one btw :celebrate:

[cimman]

ozora:

ozora:

Need guide in this question only: The number of basketballs was 3/5 of the number of footballs. In jan , 1/3 of the basketball and 1/3 of the football were sold. In feb,4 basketball n 4 footballs were sold. The number of basketballs left was 1/2 of the number of footballs. How many basketballs were there at first?


Thanks

Anyone can help?

ozora, check your pm. verykiasumummy's solution is correct, though as Lotto has said, it is not so easy to 'see'. Most children will not be able to 'see' that 2u = 4 and if the numbers are larger, it is not easy to process.

[verykiasumummy]

ozora:

verykiasumummy:

[quote=\"ozora\"]Need guide in this question only: The number of basketballs was 3/5 of the number of footballs. In jan , 1/3 of the basketball and 1/3 of the football were sold. In feb,4 basketball n 4 footballs were sold. The number of basketballs left was 1/2 of the number of footballs. How many basketballs were there at first?


Thanks

just trying to help.

The number of basketballs was 3/5 of the number of footballs.

means ratio of basket:foot is 3:5.

In jan , 1/3 of the basketball and 1/3 of the football were sold.

so ratio has to be multiplied by 3.
basket : foot
9 : 15
-3u -5u
---------------
6 : 10

In feb,4 basketball n 4 footballs were sold.

basket : foot
6 : 10
-4 -4
---------------
1 : 2

since 6u-2u=4u, and 10u-2u=8u, which is exactly half, therefore

2u --> 4
1u --> 2
at first there were 9u basketball, so
9u --> 18

ans is 18.

think there is a mistake. the subtraction of basket is 6u-1u =5u .
therefore cannot be half.[/quote]its 6u-2u, not 6u-1u.. the answer is correct..

[ozora]

[basketballs was 3/5 of the number of footballs. In jan , 1/3 of the basketball and 1/3 of the football were sold. In feb,4 basketball n 4 footballs were sold. The number of basketballs left was 1/2 of the number of footballs. How many basketballs were there at first?


Thanks[/quote]

just trying to help.

The number of basketballs was 3/5 of the number of footballs.

means ratio of basket:foot is 3:5.

In jan , 1/3 of the basketball and 1/3 of the football were sold.

so ratio has to be multiplied by 3.
basket : foot
9 : 15
-3u -5u
---------------
6 : 10

In feb,4 basketball n 4 footballs were sold.

basket : foot
6 : 10
-4 -4
---------------
1 : 2

since 6u-2u=4u, and 10u-2u=8u, which is exactly half, therefore

2u –> 4
1u –> 2
at first there were 9u basketball, so
9u –> 18

ans is 18.[/quote]
think there is a mistake. the subtraction of basket is 6u-1u =5u .
therefore cannot be half.[/quote]
okie i c the error. thanks for highlighting in using parts and units

[KP2]

lotto:

KP2:

Need help with Nanyang primary 2011 SA2 paper 2 question no 16.

Hi KP2,

If this is the question that u mean,

[i]Mr Chen bought some pencil cases and bags for the children at a gathering. The price of each pencil case was $2.40 while the price of each bag was $10.80. For every 4 bags bought, he was given one such pencil case for free. After receiving the free pencil cases, the number of pencil cases was 1/3 of the number of bags bought.
If Mr Chen paid a total of $1584, how much more did he pay for the bags
than the pencil

The answer key is wrong I think :scratchhead:
Hope mine is correct and can be understood.
But it is way too messy :imsorry:
I'm still not use to post solution here

Thx Lotto ! Ur answer is the same as the answer key .

[lotto]

KP2:

lotto:

[quote=\"KP2\"]Need help with Nanyang primary 2011 SA2 paper 2 question no 16.

Hi KP2,

If this is the question that u mean,

[i]Mr Chen bought some pencil cases and bags for the children at a gathering. The price of each pencil case was $2.40 while the price of each bag was $10.80. For every 4 bags bought, he was given one such pencil case for free. After receiving the free pencil cases, the number of pencil cases was 1/3 of the number of bags bought.
If Mr Chen paid a total of $1584, how much more did he pay for the bags
than the pencil

The answer key is wrong I think :scratchhead:
Hope mine is correct and can be understood.
But it is way too messy :imsorry:
I'm still not use to post solution here

Thx Lotto ! Ur answer is the same as the answer key .[/quote]


Your welcome.
Why is mine wrong... Grrr :mad:

[lotto]

ozora:

okie i c the error. thanks for highlighting in using parts and units

Or u can times 4 to the ratio in the end since the difference is always the same :evil:

[aps]

Hi all


I need help to solve this qn urgently. Thanks in advance.

John always gives 20% of what he earns to his father. In March, his father received $185 less than in February. In April, his father received $165.75 more than in March. If John’s percentage decrease in earning from February to March was the same as the percentage increase from March to April, how much did he earn in April?

[Xiao Hu]

lotto:

KP2:

Hi KP2,

If this is the question that u mean,

[i]Mr Chen bought some pencil cases and bags for the children at a gathering. The price of each pencil case was $2.40 while the price of each bag was $10.80. For every 4 bags bought, he was given one such pencil case for free. After receiving the free pencil cases, the number of pencil cases was 1/3 of the number of bags bought.
If Mr Chen paid a total of $1584, how much more did he pay for the bags
than the pencil

The answer key is wrong I think :scratchhead:
Hope mine is correct and can be understood.
But it is way too messy :imsorry:
I'm still not use to post solution here



Thx Lotto ! Ur answer is the same as the answer key .

Your welcome.
Why is mine wrong... Grrr :mad:

Hi Lotto,
Looks like you are assuming the number of bags bought are multiples of 4. Can it not be multiples of 4? If say, number of bags bought is 6, then free pencil case is 2. So he may have bought 1 more pencil case, then ratio of pencil case to bag is 2/6 = 1/3, which is what the end ratio is. But the starting ratio is not 1/4 (1 free pencil case to 6 bags).

I don't know how to solve it in any other way though.

May be gurus like Tianzhu and MathIzzzzFun can help us here?

Thanks,
Xiaohu.

[Udon]

Need help...thanks


Q1. The height of the water level in a tank rose from 80 cm to 1.16 m. Express the increase in the height of the water level as a percentage of the original height of the water level.

How to calculate the original height?


Q2. Peter took 30 minutes to clean his father's car while his elder brother only took 15 minutes to clean it. How long would both of them take to clean the car together?

It's Average calculation method right? I tried to add and divide but still could not find the answer....