Tutor MathsGuru: Ask me for your burning Maths questions!

[Ngserene617]

Thanks alot iFtuit:)

iFruit:

Ngserene617:

Hi,

Appreciate if anyone can help me the below ques:

1. Adeline has $40 which is made up of fifty-cent and twenty-cent coins. There are 50 fifty-cent coins. What percentage of the number of his coins us twenty-cent coins?

Thanks

Hi Ngserene617,

We just need to list down the facts given.

Total money Adeline has = $40
fifty cent coins = 50
Value of fifty cent coins = 0.50 * 50 = $25

amount of money in twenty cent coins = $40 - $25 = $15
Number of twenty cent coins = $15/0.2 = 1500cents/20cents = 75

Total number of coins = 75+50 = 125

% of twenty cent coins = 75/125 *100 = 60%

Hope this helps.

[Herbie]

I have one qn


There were 2 identical flights of steps. For the first of steps, Bobby walked up some steps and ran 9 steps in a total of 78 seconds. For the 2nd flight of steps, Bobby walked up some steps and ran 17 steps in a total of 48 seconds. How long will bobby take to walk up both flights of steps??

Please advise.

Tq

[Emelyn]

iFruit:

Emelyn:

Hi,


I have 3 questions and appreciate some help here.

1. Daniel's savings was 75% as much as Annabel. After annabel saved another $40 and Daniel saved another $20, Daniel's savings became 5/8 as much as Annabel's savings. Find Daniel's savings at first.

2. A box contained some square and round cookies. 40% of these cookies are round. After removing 55 squares and 10 round cookies, the number of square cookies became 70% as many as the number of round cookies. How many cookies were there in the box at first ?

3. On a bus, there were 20% as many children as adults. After 28 adults alighted from the bus, the percentage of children increased to 40%. How many children were there in the bus?

MTIA.

1)
Annabel = 4u
Daniel = 3u

After more savings,
Annabel = 4u + 40
Daniel = 3u +20

(3u+20)/(4u+40) = 5/8

24u+160 = 20u+200
4u = 40

Daniel = 3u = 30

The other problems are very similar.

Thanks. But at P5, they have not been taught Algebra yet.

[Emelyn]

Brenda10:

Emelyn:

Hi,


I have 3 questions and appreciate some help here.

1. Daniel's savings was 75% as much as Annabel. After annabel saved another $40 and Daniel saved another $20, Daniel's savings became 5/8 as much as Annabel's savings. Find Daniel's savings at first.

2. A box contained some square and round cookies. 40% of these cookies are round. After removing 55 squares and 10 round cookies, the number of square cookies became 70% as many as the number of round cookies. How many cookies were there in the box at first ?

3. On a bus, there were 20% as many children as adults. After 28 adults alighted from the bus, the percentage of children increased to 40%. How many children were there in the bus?

MTIA.

DD working:

Q1.
D:A
3:4
+20 +40
5:8

24U =160
20U =200
------------
4u = 40
1u = 10

Daniel saving at first: 3u x 10= $30

Q2.
S:Q
3:2 (Before)
-55 - 10
7:10 (After)

30u 550
14u 70
---------
16u 480
1u = 30

Cookie at first 5u x 30 = 150

Q3.

C:A
1:5 (at First)
-28 (28 audlts alighted)
2:3 (after)

2:10 (at first x 2 since no changes in children)
2:3
--------
7u = 28
1u = 4

As such, children 2u x 4 = 8

Thank you.

Hi Brenda10,

Can you explain why

24U=160
20U=200

?

Sorry...I am not very good with maths....

[Brenda10]

Emelyn:

Thanks Brenda10

Hi Emelyn

You're welcome. tks

[YLH88]

Hi all,


Need help urgently on the below question :

Percentage P6 2010 SA2 HHK P2 Q16
Yanling had 60% more stamps than Lena. Tricia had 75% fewer stamps than Yanling. Yanling and Lena gave Tricia some stamps in the ratio 4 : 1. As a result, Tricia had 2½ times as many stamps as before and Yanling had 300 stamps more than Lena in the end. How many stamps did Lena give to Tricia? [5 marks][Answer given: 150 stamps]

I saw somewhere in the post the solution is :

[quote]Y L T
--------------------------------------------------
8 : 5 : 2 = 40 : 25 : 10
- 4 : - 1 : + 5 = - 12 : - 3 : + 15
--------------------------------------------------
28 22 25
--------------------------------------------------

6 u --> 300
1 u --> 300/6 = 50

3 u --> 3 x 50 = 150 stamps

It was 50 stamps.
[/quote]But I don't understand why need to change the ratio to 40 : 25 : 10 and
-12 : -3 : +15 :?

Need to know the answer urgently as PSLE maths paper is tomorrow

Thank you!

[Emelyn]

Brenda10:

Emelyn:

Thanks Brenda10

Hi Emelyn

You're welcome. tks

Sorry... Brenda10...I actually thought I understood... but then I realised that I didn't. :oops:

Can you explain how you get

24U = 160
20U = 200

?

[Brenda10]

Emelyn:

Brenda10:

[quote=\"Emelyn\"]Thanks Brenda10

Hi Emelyn

You're welcome. tks

Sorry... Brenda10...I actually thought I understood... but then I realised that I didn't. :oops:

Can you explain how you get

24U = 160
20U = 200

?[/quote]Q1.
D:A
3:4
+20 +40
5:8
24U =160
20U =200

Use cross-multiplication (end units : 5 and 8 respectively)
(3u + 20)*8 = 24u 160
(4u + 40)*5 = 20u 200

[Emelyn]

Brenda10:

Emelyn:

[quote=\"Brenda10\"]
Hi Emelyn

You're welcome. tks

Sorry... Brenda10...I actually thought I understood... but then I realised that I didn't. :oops:

Can you explain how you get

24U = 160
20U = 200

?

Q1.
D:A
3:4
+20 +40
5:8
24U =160
20U =200

Use cross-multiplication (end units : 5 and 8 respectively)
(3u + 20)*8 = 24u 160
(4u + 40)*5 = 20u 200[/quote]Ok. Understand now how you get 24U 160....
But...paiseh hor...... why need to cross multiply lei ?? What are we trying to achieve ?
:oops: :oops: :oops:

[Vanilla Cake]

Herbie:

There were 2 identical flights of steps. For the first of steps, Bobby walked up some steps and ran 9 steps in a total of 78 seconds. For the 2nd flight of steps, Bobby walked up some steps and ran 17 steps in a total of 48 seconds. How long will bobby take to walk up both flights of steps??

Difference in steps = 17-9 = 8
Difference in time = 78-48 = 30 s

It took Bobby 30s more to walk up 8 steps than running 8 steps
8 steps -> 30 s
1 step -> 3.75 s
meaning to say that it took Bobby 3.75 s more to walk up one step

9 steps -> 9x3.75 s = 33.75s
It took Bobby 33.75 s more to walk up 9 steps

Time taken = Time running + time of walking
= 78 s + 33.75 s more
=111.75 s for walking up 1 flight of steps.

Total time-> 2x111.75 = 223.5 s
Time taken for Bobby to walk up both flights of steps = 223.5 s

VC's mum