Q&A - PSLE Math
-
Mr.Lee left town P at 6.45am? did u miss the P?
Also the correct thread for these is here :
http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=280&start=8950 -
Mr Lee start 6.45 ; speed 60kmh
At 10.15 (3.5h later) ; Mr Lee travel 60+60+60+30=210km already
Mrs Chen took 3h (7.15 to 10.15) to travel 210km (catch up Mr Lee)
Mrs Chen Speen is 70kmh.
Mrs Chen need to travel another 350km to reach Q ie another 5h
Another 5h, Lee travel 300km only…still 50km away… -
Hi,
Can someone enlighten me the below question with two types of method to solve the question but why different answer? Please advise the mistake. I suppose no matter which methods should also get the same answer. Thank you.
A box contained some twenty-coins and some fifty-cent coins in the ratio 3:4. When 26 fifty-cent coins were taken out and replaced by the same number of twenty-cent coins, the ratio became 4:1. Find the sum of money in the box in the box at first.
Working No 1
Since the number of coins did not change, we make the total the same
Before
T : F
3 : 4 (Total = 7u)
15 : 20 (Total = 35u)
After
T : F
4 : 1 (Total = 5u)
28 : 7 (Total = 35u)
13u = 26
1u = 2
15u of 20 cent = 15 x 2 x 0.2 = $6
20u of 50 cent = 20 x 2 x 0.5 = $20
Total = $26
Working No 2
Using units and parts
20cents : 50cents
3 units : 4 units
+65 -26 x 4
4 parts 1 part
3u +65 = 4p
16u -104 = 4p
3u + 65 = 16u - 104
16u - 3u = 65 + 104
13u = 169
u = 13
3u = 13 x 3 = 39
39 x $0.20 = $7.80
4u = 13 x 4 = 52
52 x $0.50 = $26
$7.80 + $26. = $33.80 -
Musicstar:
Hi,Hi,
Can someone enlighten me the below question with two types of method to solve the question but why different answer? Please advise the mistake. I suppose no matter which methods should also get the same answer. Thank you.
A box contained some twenty-coins and some fifty-cent coins in the ratio 3:4. When 26 fifty-cent coins were taken out and replaced by the same number of twenty-cent coins, the ratio became 4:1. Find the sum of money in the box in the box at first.
Working No 1
Since the number of coins did not change, we make the total the same
Before
T : F
3 : 4 (Total = 7u)
15 : 20 (Total = 35u)
After
T : F
4 : 1 (Total = 5u)
28 : 7 (Total = 35u)
13u = 26
1u = 2
15u of 20 cent = 15 x 2 x 0.2 = $6
20u of 50 cent = 20 x 2 x 0.5 = $20
Total = $26
Working No 2
Using units and parts
20cents : 50cents
3 units : 4 units
+65 -26 x 4
4 parts 1 part
3u +65 = 4p
16u -104 = 4p
3u + 65 = 16u - 104
16u - 3u = 65 + 104
13u = 169
u = 13
3u = 13 x 3 = 39
39 x $0.20 = $7.80
4u = 13 x 4 = 52
52 x $0.50 = $26
$7.80 + $26. = $33.80
This is because in (b), instead of replaced with same number of coins, it is substituted with same amount of coins.
i.e. 65x20cents= 26x50cents in amount
But the question said \"same number\" though.
Regards -
Oldschool,
Thank you for pointing out to me. I am really careless and did not read the question properly. The two words are really important. If don't have these two words \"the same\" which mean I need to change to the number of coin to the amount.Oldschool:
Hi,Musicstar:
Hi,
Can someone enlighten me the below question with two types of method to solve the question but why different answer? Please advise the mistake. I suppose no matter which methods should also get the same answer. Thank you.
A box contained some twenty-coins and some fifty-cent coins in the ratio 3:4. When 26 fifty-cent coins were taken out and replaced by the same number of twenty-cent coins, the ratio became 4:1. Find the sum of money in the box in the box at first.
Working No 1
Since the number of coins did not change, we make the total the same
Before
T : F
3 : 4 (Total = 7u)
15 : 20 (Total = 35u)
After
T : F
4 : 1 (Total = 5u)
28 : 7 (Total = 35u)
13u = 26
1u = 2
15u of 20 cent = 15 x 2 x 0.2 = $6
20u of 50 cent = 20 x 2 x 0.5 = $20
Total = $26
Working No 2
Using units and parts
20cents : 50cents
3 units : 4 units
+65 -26 x 4
4 parts 1 part
3u +65 = 4p
16u -104 = 4p
3u + 65 = 16u - 104
16u - 3u = 65 + 104
13u = 169
u = 13
3u = 13 x 3 = 39
39 x $0.20 = $7.80
4u = 13 x 4 = 52
52 x $0.50 = $26
$7.80 + $26. = $33.80
This is because in (b), instead of replaced with same number of coins, it is substituted with same amount of coins.
i.e. 65x20cents= 26x50cents in amount
But the question said \"same number\" though.
Regards -
Anyone can help?
There were a total of 20800 toys in Factory A and Factory B. After 3/4 of toys in Factory A and 3/5 in Factory B were sold, there were 1040 more toys in B than A. How many toys were there in each factory at first? -
rocklee:
hihiAnyone can help?
There were a total of 20800 toys in Factory A and Factory B. After 3/4 of toys in Factory A and 3/5 in Factory B were sold, there were 1040 more toys in B than A. How many toys were there in each factory at first?
there is a solution http://www.kiasuparents.com/kiasu/forum/viewtopic.php?p=775568#p775568/
-
-
Please help.Thank you
Q11) Sally , Yiling and Ali shared a bag of beads. Sally received 3/4 of the bag of beads and 3/4 of a bead. Yiling received 3/4 of the remaining bag of beads and 3/4 of a bead. Ali received the last bead in the bag. How many beads did Sally receive? (No bead was to be divided in any way)
Q17 ) Jane and Iris had 255 sweets altogether. Jane had 15 more sweets than Iris. Jane gave away 25% as many sweets as Iris. She was left with twice as many sweets as Iris.
(a) How many sweets did Iris give away?
(b) How many sweets did Jane have in the end? -
Musicstar:
............................................[---------------1u-------------]Please help.Thank you
Q11) Sally , Yiling and Ali shared a bag of beads. Sally received 3/4 of the bag of beads and 3/4 of a bead. Yiling received 3/4 of the remaining bag of beads and 3/4 of a bead. Ali received the last bead in the bag. How many beads did Sally receive? (No bead was to be divided in any way)
[--------------------3u-------------------][3/4][------3p------][3/4][ 1]
...................................................................[---1p--]
S [--------------------3u-------------------][3/4]
Y [------3p------][3/4]
A [ 1]
1p --> 1 + 3/4 = 7/4
4p --> 7
1u --> 3/4 + 4p = 3/4 + 7 = 31/4
Sally --> 3u + 3/4 = 3*(31/4) + 3/4 = 96/4 = 24
Hello! It looks like you're interested in this conversation, but you don't have an account yet.
Getting fed up of having to scroll through the same posts each visit? When you register for an account, you'll always come back to exactly where you were before, and choose to be notified of new replies (either via email, or push notification). You'll also be able to save bookmarks and upvote posts to show your appreciation to other community members.
With your input, this post could be even better 💗
Register Login