Q&A - P5 Math

[shawnlim88]

concerned1970:

4) Mr F had a sum of money. He gave half of his money plus $570 to his wife. He gave half of the remainder plus $420 to his parents. Then he gave half of the remainder to his daughter, Abby. He also bought a dress that cost $89 for Abby. If Mr F was left with $568, how much money did he have at first?

<------------------------------ WIFE --------------------------->
<---------------------------------------------------------->|570|
<------------------------>|420|<---------Parent------->|
<----------->|<--Abby->|
<568>|<89>
so:
<568>|<89>
|<--Abby-->|420|
<----Parent----->|
<---------------->|570|
<------WIFE ---------->

568 + 89(dress) = 657
abby gest 657
before giving abby: 657*2 = 1314

parents get: additional 420 = 1734
before giving parents: 1734*2= 3468

wife gets additional 570 : 4038
before giving wife: 4038*2 = 8076

answer: $8076

hope it helps.
i don't think a P5 student is able to solve this under exam condition.
:stupid: :stupid: :stupid:

[CloudeeDaz]

concerned1970:

4) Mr F had a sum of money. He gave half of his money plus $570 to his wife. He gave half of the remainder plus $420 to his parents. Then he gave half of the remainder to his daughter, Abby. He also bought a dress that cost $89 for Abby. If Mr F was left with $568, how much money did he have at first?

do not know how to present in a better way
hope i dont confuse you

working backwards

Mr F left --->$89 + $568 = $657

$657 x 2= $1314
$1314 + $420 = $1734
$1734 x 2 = $3468
$3468 + $570 = $4038
$4038 x 2 = $8076 (ans)

edit : haha..ninja'd

[shawnlim88]

http://i48.tinypic.com/2pskrcw.jpg\"> dear all,

how to solve this: Henry Park 2011 SA2 Paper2, Qn13

thanks

[concerned1970]

Tysm for yr explanation, Shawn and Cloude. I tried to upload the exam paper but in vain. How did u guys do that?

[concerned1970]

shawnlim88:

MathIzzzFun:

[quote=\"concerned1970\"]Hi, is there anyone who can help me to solve the following ques from CHIJ 2008's paper. Ques are 7, 11, 35, 36, 40, 45 and 47. Pls do not use algebra. Ty in adv.

SA1 or SA2?

You may want to try to upload the question as jpg here. Here's how you can do it:

1) open the file
2) cut out the question using snipping tool (windows 7) or you can also download \"picpick\" from the internet.
3) save as jpg and upload here

cheers.

hi concerned1970
CHIJ 2008 SA1 or SA2??
i can cut and post the questions for you.

pls specifiy

shawnlim88[/quote]Hi Shawn, yes u r right. Actually I did follow Tianzhu's method and then taught my DS but somehow he got it wrong then I realized there are two left over instead of one left over and the other is short of. So got to add. Ty for yr detailed explanation. It helps a lot. How did u cut the paper using Microsoft word? Of cos it's SA2, now it's end yr exam loll. Appreciate yr help. If u dun mind, pls help me to solve ques fr CHIJ 2009 SA2, ques 44 and 48

[concerned1970]

Pls help me to solve last two pb sums. Tia

1) A frog is at the bottom of a well which is 31m deep. It climbs 6m up in the day and slides 4m down at night. How many days does it take for a frog to get out of the well?

2) Nathan withdrew 80% of his savings to purchase a laptop. If he were given a 15% discount on the cost price of the laptop, he could have put $390 back into his savings account. A) How much did he pay for the laptop? B) How much did Nathan have in his savings account at first?

[verykiasumummy]

concerned1970:

Pls help me to solve last two pb sums. Tia

1) A frog is at the bottom of a well which is 31m deep. It climbs 6m up in the day and slides 4m down at night. How many days does it take for a frog to get out of the well?

2) Nathan withdrew 80% of his savings to purchase a laptop. If he were given a 15% discount on the cost price of the laptop, he could have put $390 back into his savings account. A) How much did he pay for the laptop? B) How much did Nathan have in his savings account at first?

hi, offering my help :

Q1
It climbs 6m up in the day and slides 4m down at night
6m - 4m = 2m (means each day, the frog climbs 2m)
31m - 6m = 25m (we take it that from the last day if the frog climbs from where it was, it should be from anywhere from the 25m onwards and it would jump out of the well)
25m / 2m = 12.5 ~ 13 days.
13 x 2m = 26m
26m + 6m = 32m (out of the well.
so 13 days + 1 day = 14 days (Ans)


Q2
If he were given a 15% discount on the cost price of the laptop, he could have put $390 back into his savings account.
15% --> $390
1% --> $26
100% --> $2600 (Ans for (a))

80% of savings --> $2600
10% of savings --> $325
100% of savings --> $3250 (Ans for (b))

[concerned1970]

verykiasumummy:

concerned1970:

Pls help me to solve last two pb sums. Tia

1) A frog is at the bottom of a well which is 31m deep. It climbs 6m up in the day and slides 4m down at night. How many days does it take for a frog to get out of the well?

2) Nathan withdrew 80% of his savings to purchase a laptop. If he were given a 15% discount on the cost price of the laptop, he could have put $390 back into his savings account. A) How much did he pay for the laptop? B) How much did Nathan have in his savings account at first?

hi, offering my help :

Q1
It climbs 6m up in the day and slides 4m down at night
6m - 4m = 2m (means each day, the frog climbs 2m)
31m - 6m = 25m (we take it that from the last day if the frog climbs from where it was, it should be from anywhere from the 25m onwards and it would jump out of the well)
25m / 2m = 12.5 ~ 13 days.
13 x 2m = 26m
26m + 6m = 32m (out of the well.
so 13 days + 1 day = 14 days (Ans)


Q2
If he were given a 15% discount on the cost price of the laptop, he could have put $390 back into his savings account.
15% --> $390
1% --> $26
100% --> $2600 (Ans for (a))

80% of savings --> $2600
10% of savings --> $325
100% of savings --> $3250 (Ans for (b))

Tysm for yr help. But for ques 1 which u have answered, the correct ans shown is 32 days.

[verykiasumummy]

concerned1970:

verykiasumummy:

[quote=\"concerned1970\"]Pls help me to solve last two pb sums. Tia

1) A frog is at the bottom of a well which is 31m deep. It climbs 6m up in the day and slides 4m down at night. How many days does it take for a frog to get out of the well?

2) Nathan withdrew 80% of his savings to purchase a laptop. If he were given a 15% discount on the cost price of the laptop, he could have put $390 back into his savings account. A) How much did he pay for the laptop? B) How much did Nathan have in his savings account at first?

hi, offering my help :

Q1
It climbs 6m up in the day and slides 4m down at night
6m - 4m = 2m (means each day, the frog climbs 2m)
31m - 6m = 25m (we take it that from the last day if the frog climbs from where it was, it should be from anywhere from the 25m onwards and it would jump out of the well)
25m / 2m = 12.5 ~ 13 days.
13 x 2m = 26m
26m + 6m = 32m (out of the well.
so 13 days + 1 day = 14 days (Ans)


Q2
If he were given a 15% discount on the cost price of the laptop, he could have put $390 back into his savings account.
15% --> $390
1% --> $26
100% --> $2600 (Ans for (a))

80% of savings --> $2600
10% of savings --> $325
100% of savings --> $3250 (Ans for (b))

Tysm for yr help. But for ques 1 which u have answered, the correct ans shown is 32 days.[/quote]to calculate on daily basis for Q1 :
day 1 : + 6m, - 4m = 2m
day 2 : 2m + 6m - 4m = 4m
day 3 : 4m + 6m - 4m = 6m
day 4 : 6m + 6m - 4m = 8m
day 5 : 8m + 6m - 4m = 10m
day 6 : 10m + 6m - 4m = 12m
day 7 : 12m + 6m - 4m = 14m
day 8 : 14m + 6m - 4m = 16m
day 9 : 16m + 6m - 4m = 18m
day 10 : 18m + 6m - 4m = 20m
day 11 : 20m + 6m - 4m = 22m
day 12 : 22m + 6m - 4m = 24m
day 13 : 24m + 6m - 4m = 26m
day 14 : 26m + 6m = 32m (already out of well)

the ans is still 14 days... is your ans sheet wrong?

[concerned1970]

Ty verykiasumummy and quekcc. I don’t know, verykiaumummy. It’s CHIJ SA2 paper 2009 I suppose. No working is shown only ans provided.