dido:

Hi,


I am trying to help my P6 child in his Math revision, but I couldn't solve. Can someone help? Thanks a million.

http://i66.tinypic.com/2drcr4z.jpg\">

God Bless

15(a) 14 cm × 756.25 cm² =10,587.5 cm³.

15(b) Let X be the water level of Tank B after all the pouring is done.

Then (X - 20) cm is the increase in the water level of Tank B and (28 - X) cm is the decrease in the water level of Tank A.

If the water level in Tank A falls by 1 cm, then its volume decreases by 1 cm × 756.25 cm² = 756.25 cm³.

If the water level in Tank B rises by 1 cm, then its volume increases by 1 cm × 5 cm × 5 cm = 25 cm³.

We know moreover that the increase in volume of water in Tank B equals the decrease in volume of water in Tank A. Therefore:

(X - 20) × 25 = (28 - X) × 756.25.

Do the algebra:

⇒ (25 + 756.25) X = 28 × 756.25 + 20 × 25

⇒ 781.25X = 21675

⇒ X = 27.744.

Hope this helps and feel free to ask for any clarifications.

- Dr. Choo Yan Min

http://www.EconsPhDTutor.com

If you found this answer helpful, then please help me out by spreading word of my services. I’m a new tutor in Singapore so I need some help getting word out! Thank you!

Steadyberry:

pls help. thank you very much.


a motorcycle travelled 75km in 45 mins and later increased its speed by 20% for the next 150km. what was the average speed of the motorcycle for the whole journey?

During the first 45 mins, its average speed was 100 km/h.

We are told that for the remaining 150 km, its average speed was 120 km/h. And so it would have taken 1 hr 15 min to travel that 150 km.

Altogether, it took 2 hours to travel 225 km. And so the average speed for the whole journey was 112.5 km/h.

Hope this helps and feel free to ask for any clarifications.

- Dr. Choo Yan Min

http://www.EconsPhDTutor.com

If you found this answer helpful, then please help me out by spreading word of my services. I’m a new tutor in Singapore so I need some help getting word out! Thank you!

questionable_i:

Can anyone help me with these questions? Thank you


http://i65.tinypic.com/oh1c1s.jpg\">

http://i68.tinypic.com/316x2px.jpg\">

(13) The shaded triangle in △ABC has the same base as, but ½ the height of △ABC. Thus, it has ½ the area of △ABC.

Thus ▱ABCD has area 4 × 14 = 56 cm².

(15) Let F be the number of 5-bead packets and S be the number of 7-bead packets.

Then the total number of packets is F + S and the total number of beads is 5F + 7S. The ratio of the former to the latter is (F + S) ÷ (5F + 7S). We are told that this ratio is 5:29.

Cross-multiplying, we have 29 (F + S) = 5 (5F + 7S).

Doing the algebra, 4F = 6S. Rearranging, S:F = 4:6. That is, there are four 7-bead packets for every six 5-bead packets. Hence, 40% or ⅖ of all packets contain 7 beads.

Hope this helps and feel free to ask for any clarifications.

- Dr. Choo Yan Min

http://www.EconsPhDTutor.com

If you found this answer helpful, then please help me out by spreading word of my services. I’m a new tutor in Singapore so I need some help getting word out! Thank you!

Special-one:

A box of pens was divided equally among 32 children.8 of these children gave up 2/5 of their share. As a result, the remaining children each received 4 more pens. How many pens were there in the box?


Anyone pls help?

Let X be the total number of pens (and hence the desired answer).

Each child received X/32 pens.

8 children gave up ⅖ × (X/32) pens, presumably redistributed equally amongst the remaining 24 children.

Hence, 8 × ⅖ × (X/32) ÷ 24 = 4.

So X = 960.




Hope this helps and feel free to ask for any clarifications.

- Dr. Choo Yan Min

http://www.EconsPhDTutor.com

If you found this answer helpful, then please help me out by spreading word of my services. I’m a new tutor in Singapore so I need some help getting word out! Thank you!

Special-one:

Anyone know how to solve?


Elton had $350 more than John. Every day, Elton spent $30 while John spent $10.When Elton had spent alll his money, John still had $50 left.

a) How many days did elton take to spend all his money?
b) How much money did Elton have at first?

[1] J = E - 350,
[2] E - 30x = 0 ⇔ E = 30x,
[3] J - 10x = 50.

Plug [1] into [3] to get

E - 350 - 10x = 50 ⇔ [4] E = 400 + 10x.

Comparing [2] and [4], we have 30x = 400 + 10x and so x = 20.

Elton took 20 days to spend all his money.

E = 30x = 600.

Elton had $600 at first.

Hope this helps and feel free to ask for any clarifications.

- Dr. Choo Yan Min

http://www.EconsPhDTutor.com

If you found this answer helpful, then please help me out by spreading word of my services. I’m a new tutor in Singapore so I need some help getting word out! Thank you!

S-H:

Hi I can't find where to put this question, this is a sec 2 maths question, can someone kindly help me with this, thank you!


(a) Solve the following inequality:-
4x - 3
------- < 5x + 2
7

(b) Write down the smallest integer that satisfies this inequality

(4x - 3) ÷ 7 < 5x + 2

⇔ 4x - 3 < 35x + 14

⇔ - 17 < 31x

⇔ - 17 ÷ 31 < x

The solution is x > -17/31.

The smallest integer that satisfies this inequality is 0.

Hope this helps and feel free to ask for any clarifications.

- Dr. Choo Yan Min

http://www.EconsPhDTutor.com

If you found this answer helpful, then please help me out by spreading word of my services. I’m a new tutor in Singapore so I need some help getting word out! Thank you!

chloecube:

Ann and ben share the cost of present. Ann paid $8 more than 3/7 of the present. Ben paid $64 for the present.how much is the present.


Anyone can help? Tks!

We are given:

(1) A = 8 + (3/7) × P.
(2) B = 64.

We are also implicitly given:

(3) A + B = P.

⇔ 8 + (3/7) × P + 64 = P

⇔ 72 + (3/7) × P = P

⇔ 72 = (4/7) × P

⇔ P = (7/4) × 72 = 126.

Hope this helps and feel free to ask for any clarifications.

- Dr. Choo Yan Min

http://www.EconsPhDTutor.com

If you found this answer helpful, then please help me out by spreading word of my services. I’m a new tutor in Singapore so I need some help getting word out! Thank you!

wilburlim:

I need help for this question:


Amos, Ben and Charles shared the cost of a present. Amos and Ben paid 5/9 of the price of the present. Amos and Charles paid 2/3 of the price of the present. Amos paid $4. How much did the present cost?

Thank you! :boogie:

Let A, B, and C be the amounts paid by each. Let X be the cost of the present.
We are told that

(1) A + B = (5/9) X,
(2) A + C = (2/3) X,
(3) A = $4.

Add (1) and (2) together to get

(4) 2A + B + C = (11/9) X.

But we know that

(5) A + B + C = X.

And so (4) minus (5) yields

(6) A = (2/9) X.

Together with (3), we have X = (9/2) × $4 = $18.


Hope this helps and feel free to ask for any clarifications.

- Dr. Choo Yan Min

http://www.EconsPhDTutor.com

If you found this answer helpful, then please help me out by spreading word of my services. I’m a new tutor in Singapore so I need some help getting word out! Thank you!

chloecube:

Hi

need help on this

there are 2617 vehicle in a carpark
the number of lorries was 353 less than the number of vans but 562 more than the total number of cars and motocycles. the motorcycles and cars have 1150 wheels altogether.
how many cars are there in the carpark?

tricky part is the wheel...

anyone can help? thks

Sorry, I initially made a mistake by mis-typing one number. Now corrected with strikeout below. The answer is C = 195.

We have four pieces of information:

(1) L + V + C + M = 2617
(2) L + 353 = V
(3) L - 562 = C + M
(4) 4C + 2M = 1150

Plug (2) and (3) into (1) to get:

L + (L + 353) + (L - 562) = 3L - 209 = 2̶1̶6̶7̶ 2617
⇒ 3L = 2826
⇒ L = 942

Plug L = 792 into (3) to get 380 = C + M.

Rewrite (4) as 2C + 2 × (C + M) = 1150.

Now plug in 230 = C + M into (4) to get 2C + 760 = 390.

⇒ 2C = 390
⇒ C = 195.

Hope this helps and feel free to ask for any clarifications.

- Dr. Choo Yan Min

http://www.EconsPhDTutor.com

If you found this answer helpful, then please help me out by spreading word of my services. I’m a new tutor in Singapore so I need some help getting word out! Thank you!

questionable_i:

Can anyone help me with these questions?


Q1 http://i.imgur.com/WMfx9Ji.jpg\">

Q2 http://i.imgur.com/O1oe1tf.jpg\">

Q3. Show that if n is a positive integer, 4^n+5(4^n+1)-2^2n+1 is divisible by 19.

Thank you

Hello.

Q1. 5^(-x).
Q2. 15/(√2).

Please see https://drive.google.com/file/d/0By83v5TWkGjvOWU1d0I3ZlAxYzA/view?usp=sharing for the full solutions.

For Q3, I think there might be a typo. Because if you try for example n = 1, we have 4^1 + 5 × (4^1 + 1) - 2^(2 × 1) + 1 = 4 + 5 × 5 - 4 + 1 = 26, which is not divisible by 19.

Hope this helps and feel free to ask for any clarifications.

- Dr. Choo Yan Min