Fig 1 -> 2 = 2 x 1milo-cupcake wrote:Hi,

Can someone help with the following question ?

Thanks in advance!

Fig 2 -> 8 = 2 x 2^2

Fig 3 -> 18 = 2 x 3^2

.

.

.

Fig n -> 2 x n^2

Academic support for Primary 5

Post
by **BigDevil** » Sat Jun 14, 2014 4:44 pm

Fig 1 -> 2 = 2 x 1milo-cupcake wrote:Hi,

Can someone help with the following question ?

Thanks in advance!

Fig 2 -> 8 = 2 x 2^2

Fig 3 -> 18 = 2 x 3^2

.

.

.

Fig n -> 2 x n^2

Post
by **belnanna** » Sat Jun 14, 2014 7:46 pm

Hi, but i dont understand the method solved. Thats why hoping to find someone whos able to explain with another method.BigDevil wrote:This had been solved before....belnanna wrote:Can anyone solve this please? Thanks in advance...............

A store sells pens in packs of 2s (small) and 4s (big).

At first there were 3 times more small packs than big packs.

After selling half of the small packs and some big packs, the shopkeeper packs

additional 5 big packs of pens. How many big packs are sold if there are thrice as many small packs as big packs and there is total 300 unsold pens?

http://www.kiasuparents.com/kiasu/forum ... 3#p1019053

Post
by **tracywham** » Sat Jun 14, 2014 10:29 pm

Hi, need help to solve this question.

Guoming has 120 fish. 3/8 of the fish are goldfish. 1/5 of them are angelfish and the rest are guppies. What fraction of the fish are guppies?

The answer in the book is17/40.. but i couldn't get it.

thank you in advance.

Guoming has 120 fish. 3/8 of the fish are goldfish. 1/5 of them are angelfish and the rest are guppies. What fraction of the fish are guppies?

The answer in the book is17/40.. but i couldn't get it.

thank you in advance.

Post
by **Jx2mum** » Sat Jun 14, 2014 11:15 pm

Common multiple of 8 and 5 is 40.tracywham wrote:Hi, need help to solve this question.

Guoming has 120 fish. 3/8 of the fish are goldfish. 1/5 of them are angelfish and the rest are guppies. What fraction of the fish are guppies?

The answer in the book is17/40.. but i couldn't get it.

thank you in advance.

Take 3/8 times 5, you get 15/40.

Take 1/5 times 8, you get 8/40.

40/40 - 15/40 - 8/40=17/40

Post
by **bb_ mom** » Sat Jun 14, 2014 11:15 pm

Fraction of goldfish and angelfish -> 3/8+1/5=15/40+8/40=23/40tracywham wrote:Hi, need help to solve this question.

Guoming has 120 fish. 3/8 of the fish are goldfish. 1/5 of them are angelfish and the rest are guppies. What fraction of the fish are guppies?

The answer in the book is17/40.. but i couldn't get it.

thank you in advance.

Fraction of guppies -> 40/40-23/40=17/40

Post
by **nansk** » Sun Jun 15, 2014 12:29 am

I didn't understand that solution either. And ifbelnanna wrote:Hi, but i dont understand the method solved. Thats why hoping to find someone whos able to explain with another method.BigDevil wrote:This had been solved before....belnanna wrote:Can anyone solve this please? Thanks in advance...............

A store sells pens in packs of 2s (small) and 4s (big).

At first there were 3 times more small packs than big packs.

After selling half of the small packs and some big packs, the shopkeeper packs

additional 5 big packs of pens. How many big packs are sold if there are thrice as many small packs as big packs and there is total 300 unsold pens?

http://www.kiasuparents.com/kiasu/forum ... 3#p1019053

ETA: Okay, my dh helped me solve it. (And we got a different answer than the other solver.)

So in the "after" scenario:

(3U X 2pens) + (U X 4pens) = 300 pens

10U = 300

U = 30

So each box above = 30 packs (

You can see that in the "before" scenario, Big packs were 2U = 60 packs.

In the "after" scenario, Big pack are U = 30 packs.

Of these 30 packs, 5 packs were added later.

So actual unsold Big packs = 30 - 5 = 25 packs.

So Big packs sold = 60 - 25 =

Post
by **Ice watch** » Sun Jun 15, 2014 12:50 pm

Try backward...belnanna wrote:Hi, but i dont understand the method solved. Thats why hoping to find someone whos able to explain with another method.BigDevil wrote:This had been solved before....belnanna wrote:Can anyone solve this please? Thanks in advance...............

A store sells pens in packs of 2s (small) and 4s (big).

At first there were 3 times more small packs than big packs.

After selling half of the small packs and some big packs, the shopkeeper packs

additional 5 big packs of pens. How many big packs are sold if there are thrice as many small packs as big packs and there is total 300 unsold pens?

http://www.kiasuparents.com/kiasu/forum ... 3#p1019053

- milo-cupcake
- OrangeBelt
**Posts:**37**Joined:**Sat Jan 12,

Post
by **milo-cupcake** » Sun Jun 15, 2014 5:20 pm

Hi.

Can anyone tell me the formular/rule of this question?

Thks in advance!

Can anyone tell me the formular/rule of this question?

Thks in advance!

- PiggyLalala
- KiasuGrandMaster
**Posts:**4053**Joined:**Tue May 24,**Total Likes:**23

Post
by **PiggyLalala** » Sun Jun 15, 2014 5:26 pm

(n+1)^2 + nmilo-cupcake wrote:Hi.

Can anyone tell me the formular/rule of this question?

Thks in advance!

Post
by **nansk** » Sun Jun 15, 2014 9:22 pm

Thank you for correcting me. I see that I made a mistake in reading the bolded line of the problem. I also derived 180 small packs for the "before" scenario, but went wrong from there on.quekcc wrote:At the beginning, small pack is 3 timesnansk wrote: A store sells pens in packs of 2s (small) and 4s (big).

At firstthere were 3 times more small packs than big packs.

After selling half of the small packs and some big packs, the shopkeeper packs

additional 5 big packs of pens. How many big packs are sold if there are thrice as many small packs as big packs and there is total 300 unsold pens?

So in the "after" scenario:

(3U X 2pens) + (U X 4pens) = 300 pens

10U = 300

U = 30

So each box above = 30 packs (not30 pens)

You can see that in the "before" scenario, Big packs were 2U = 60 packs.

In the "after" scenario, Big pack are U = 30 packs.

Of these 30 packs, 5 packs were added later.

So actual unsold Big packs = 30 - 5 = 25 packs.

So Big packs sold = 60 - 25 =35 packs.morethan big pack, so there are 180 / 4 = 45 big packs.

Note that the seller actually pack additional 5 big packs, so he sold 45 + 5 - 30 = 20 big packs.

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