Tutor MathsGuru: Ask me for your burning Maths questions!

[Vanilla Cake]

firebird:

You are correct. The question 4 posted by me is incomplete. The question was given by my son's school. I am very sorry. The complete question is as follows:


A fan Club had 150 members last year. This year, the number of male members reduces by 20% and the number of females members increases by 20%. As a result, there are now as many male members as female members. How many members does the club have this year?

Dear firebird,
Thks for your clarification as it took me some time trying to figure out your question last night.

This year
Male members=100%
Female members=100%

Last year
Male members=100/80x100%=125%
Female members=100/120x100%=83⅓%

208⅓%=150
200% = 144

This year, the number of members that the club has = 144

Check
Last year
Male members: 90
Female members: 60

This year
Male members: 80/100x90=72
Female members: 120/100x60=72

Hope that I am correct while you wait for Mathsguru's solutions.
Cheers.

[Tang]

Vanilla Cake:

firebird:

You are correct. The question 4 posted by me is incomplete. The question was given by my son's school. I am very sorry. The complete question is as follows:


A fan Club had 150 members last year. This year, the number of male members reduces by 20% and the number of females members increases by 20%. As a result, there are now as many male members as female members. How many members does the club have this year?

Dear firebird,
Thks for your clarification as it took me some time trying to figure out your question last night.

This year
Male members=100%
Female members=100%

Last year
Male members=100/80x100%=125%
Female members=100/120x100%=83⅓%

208⅓%=150
200% = 144

This year, the number of members that the club has = 144

Check
Last year
Male members: 90
Female members: 60

This year
Male members: 80/100x90=72
Female members: 120/100x60=72

Hope that I am correct while you wait for Mathsguru's solutions.
Cheers.

Let me try to solve this using Ratio.

MN : FN = 1 : 1 = 12 : 12

M : MN = 100 : 80 = 5: 4 = 15: 12

F : FN = 100 : 120 = 5 : 6 = 10 : 12

M + F --> 15 + 10 = 25

25 u --> 150

1 u --> 150/25 = 6

MN + FN --> 12 + 12 = 24

24 u --> 6 x 24 = 144 members

The club has 144 members this year.

[liketoeat]

Hi, I need help with the following question…


The average mass of 5 blocks is 1.58 kg. When some identical cubes with a mass of 1.6 kg each were added to them, the average mass became 1.595 kg. How many cubes were added?

Thank you.

[Vanilla Cake]

liketoeat:

The average mass of 5 blocks is 1.58 kg. When some identical cubes with a mass of 1.6 kg each were added to them, the average mass became 1.595 kg. How many cubes were added?

Since this is a P6 question then use algebra which is good enough to solve and gain full marks.
Let number of cubes added be n
( 5x1.58 )+( nx1.6 )=( n+5 )x1.595
n=15
Number of cubes added = 15

Hope other members will forward with non-algebraic approach so that readers of this forum can learn.

[Dharma]

Vanilla Cake:

liketoeat:

The average mass of 5 blocks is 1.58 kg. When some identical cubes with a mass of 1.6 kg each were added to them, the average mass became 1.595 kg. How many cubes were added?

Since this is a P6 question then use algebra which is good enough to solve and gain full marks.
Let number of cubes added be n
( 5x1.58 )+( nx1.6 )=( n+5 )x1.595
n=15
Number of cubes added = 15

Hope other members will forward with non-algebraic approach so that readers of this forum can learn.

http://www.postimage.org/image.php?v=aVb175J

[Vanilla Cake]

Dharma:

Vanilla Cake:

[quote=\"liketoeat\"]The average mass of 5 blocks is 1.58 kg. When some identical cubes with a mass of 1.6 kg each were added to them, the average mass became 1.595 kg. How many cubes were added?

Since this is a P6 question then use algebra which is good enough to solve and gain full marks.
Let number of cubes added be n
( 5x1.58 )+( nx1.6 )=( n+5 )x1.595
n=15
Number of cubes added = 15

Hope other members will forward with non-algebraic approach so that readers of this forum can learn.

http://www.postimage.org/image.php?v=aVb175J[/quote]Thanks, Dharma for your wonderful visual solution.
This is what is known as 抛砖引玉 - 比喻说出自己粗浅的意见引出别人高明的见解.

[Tang]

Dharma:

Vanilla Cake:

[quote=\"liketoeat\"]The average mass of 5 blocks is 1.58 kg. When some identical cubes with a mass of 1.6 kg each were added to them, the average mass became 1.595 kg. How many cubes were added?

Since this is a P6 question then use algebra which is good enough to solve and gain full marks.
Let number of cubes added be n
( 5x1.58 )+( nx1.6 )=( n+5 )x1.595
n=15
Number of cubes added = 15

Hope other members will forward with non-algebraic approach so that readers of this forum can learn.

http://www.postimage.org/image.php?v=aVb175J[/quote]Increase in average --> 1.595 - 1.58 = 0.015

Total increase --> 0.015 x 5 = 0.075 kg

Decrease in average --> 1.600 - 1.595 = 0.005

So number of cubes added --> 0.075/0.005 = 15 cubes

15 cubes were added.

[Almighty]

ruyu:

Vanilla Cake:

[quote=\"YLH88\"]6) Mark can climb uphill at an average speed of 2km/h and go downhill at an average speed of 6km/h. Going first uphill and then downhill, without stopping and using the same route, what will his average speed be for the entire trip ?

Assume the distance of the route be unit.
Total time taken = unit/2 + unit/6 = 4units/6 = 2units/3
Distance = unit
Average speed = unit÷2 units/3 = unitx3/2units = 3/2 = 1.5 km/h

This is similar to NMOS 2009 Prelim round Q3. Where is this question taken from?

dont understand :? care to explain?[/quote]HI Vanilla cake,
He is asking for the entire trip. So, shouldn't it be 1.5 X 2 = 3km/h?
12kmX2 = 24Km
12/2 = 6hr
12/6 = 2hr
6+2 = 8 hr
8hr ------24km
1hr -------? (3km)

Pl.clarify

[firebird]

Dear Vanilla cake and Tang


Good afternoon.

Thank you very much for your solution.

Vanilla cake, very sorry for the incorrect question and troubling you a lot.

With best regards
firebird

[Almighty]

Almighty:

Hi Friends,


Water was poured into an empty rectangular Tank X until it reached a height of 20cm. Some of the water was then poured into Tank Y which contained 1.5 litres of water until the height of the water in both the tanks were the same.Find the new height of the water in Tank Y.

MY working is :
Volume / base area = Height
So for Tank Y, Base area = 1000 cm 2
1500 / 1000 = 1.5 cm

Height of water in Tank X - Height in Tank Y = 20 - 1.5 = 18.5cm
So, to make it same, 18.5 / 2 = 9.25cm
Therefore new Height of Tank Y = 9.25 + 1.5 = 10.75 cm

Can anyone pointout y i cannot do like this? The method followed in the assessment book is different hence the answer is also different which is 12.6cm.

Will write below the method followed by the book is:
Volume in Tank X: 50x30x20 = 30000cm3
Totla volume = 30000+ 1500 = 31500 cm3
50X30Xh+40X25h ----------- 31 500
1500 h +1000h ---- 31 500
h --- 31500/2500 = 12.6 cm
Now can anyone say where i went wrong?