Q&A - P5 Math

[imacsg]

Thanks MathIzzzFun and Tianzhu for your prompt reply.

[chloecube]

okok, i got it, thks for the detailed explaination!

[cmm]

tianzhu:

cmm:

[quote=\"tianzhu\"]
Hi

Please study Jamesbond’s question on pg 167 and pg170.

http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=68&t=25129&start=1670

http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=68&t=25129&start=1690

The answers are 190 white triangles and pattern 130.

Best wishes

Hi tianzhu, regarding the above question, can explain how to get n x (n+1)/2? Is it same as the question 1 + 2 + 3 + 4....... + n? Then are we assuming that n is an even number cos if n is odd, the we need to add the number in the middle of the set to the formula.

Also, may I know how to solve n + n x n = 17030? Is it simply square root 17030 and just take the whole number to be the answer (130)? Rather difficult to P5 who needs absolutes as answers.

Thank you!

Hi

The sequence for black triangles in your question is 1,3,6,10 .....

Please refer to the slide and look at the table on pattern number and white squares (1,3,6,10....)

It does not matter whether the pattern number is even or odd, the sequence follows n(n+1)/2.

n(n+1)/2 ------ 8815

Hence, n(n+1) ------- 17030

The multiplication of two consecutive numbers leads to 17030.With the use of calculators in primary maths, it’s not too difficult to arrive at the answer with a bit of guess and check.

Yes, you may also find the square root of 17030 and try to make some adjustment.

Best wishes[/quote]Thank you for the detailed explanation!! :salute:

[Jamesbond]

Jamesbond:

Lim had some stickers and stamps for his class. The number of stickers was half as many as the number of stamps. After each pupil in the class had received 3 stickers and 8 stamps from Lim. He had 39 stickers and 2 stamps left. What was the total number of stickers and stamps Lim had at first?


Pl help me....

Can anybody help....pl

[jieheng]

Jamesbond:

Jamesbond:

Lim had some stickers and stamps for his class. The number of stickers was half as many as the number of stamps. After each pupil in the class had received 3 stickers and 8 stamps from Lim. He had 39 stickers and 2 stamps left. What was the total number of stickers and stamps Lim had at first?


Pl help me....

Can anybody help....pl

The number of stickers was half as many as the number of stamps
Stickers (SK) 1u , Stamps (ST) 2u

SK [----------------------]
ST [----------------------]
ST [----------------------]


After each pupil in the class had received 3 stickers and 8 stamps from Lim

SK [---][---][---][------]
ST [---][---][---][---][ ]
ST [---][---][---][---][ ]

He had 39 stickers and 2 stamps left

SK [---][---][---][38][1]
ST [---][---][---][---][1]
ST [---][---][---][---][1]

the total number of stickers and stamps Mr Lim had at first
= 38*12 + 3
= 459 (Ans)

[ttyh]

5/11 of the children at a party like chocolate ice cream. 1/3 as many children like vanilla ice cream as those who like strawberry ice cream. There are 182 more children who like chocolate ice cream than vanilla ice cream. How many children are there at party altogether?

Pls help to advise if can solve this via model or via fraction method?
Thanks

[MathIzzzFun]

ttyh:

5/11 of the children at a party like chocolate ice cream. 1/3 as many children like vanilla ice cream as those who like strawberry ice cream. There are 182 more children who like chocolate ice cream than vanilla ice cream. How many children are there at party altogether?

Pls help to advise if can solve this via model or via fraction method?
Thanks

you can use any approach - fraction, ratio, model, units..

using fraction:
children who like chocolate ice-cream --> 5/11 total
children who like vanilla and strawberry ice-cream--> 6/11 total
children who like vanilla ice cream --> 1/4 x 6/11 = 6/44 total
children who like strawberry ice cream --> 3/4 x 6/11 = 18/44 total
5/11 - 6/44 = 14/44
14/44 total --> 182
Total number of children = 182/14 x 44 = 572

using ratio:
children who like chocolate : total : vanilla & strawberry = 5 : 11 : 6 = 10u : 22u : 12u
children who like vanilla : strawberry = 1 : 3 = 3u : 9u (total 12u)
10u - 3u = 7u --> 182
total number of children = 22/7 x 182 = 572

cheers.

[ttyh]

MathIzzzFun:

ttyh:

5/11 of the children at a party like chocolate ice cream. 1/3 as many children like vanilla ice cream as those who like strawberry ice cream. There are 182 more children who like chocolate ice cream than vanilla ice cream. How many children are there at party altogether?

Pls help to advise if can solve this via model or via fraction method?
Thanks

you can use any approach - fraction, ratio, model, units..

using fraction:
children who like chocolate ice-cream --> 5/11 total
children who like vanilla and strawberry ice-cream--> 6/11 total
children who like vanilla ice cream --> 1/4 x 6/11 = 6/44 total
children who like strawberry ice cream --> 3/4 x 6/11 = 18/44 total
5/11 - 6/44 = 14/44
14/44 total --> 182
Total number of children = 182/14 x 44 = 572

using ratio:
children who like chocolate : total : vanilla & strawberry = 5 : 11 : 6 = 10u : 22u : 12u
children who like vanilla : strawberry = 1 : 3 = 3u : 9u (total 12u)
10u - 3u = 7u --> 182
total number of children = 22/7 x 182 = 572

cheers.

You wrote \"children who like vanilla ice cream --> 1/4 x 6/11 = 6/44 total \"
can u help to explain how the 1/4 is being derived? Thanks

[MathIzzzFun]

ttyh:

MathIzzzFun:

[quote=\"ttyh\"]5/11 of the children at a party like chocolate ice cream. 1/3 as many children like vanilla ice cream as those who like strawberry ice cream. There are 182 more children who like chocolate ice cream than vanilla ice cream. How many children are there at party altogether?

Pls help to advise if can solve this via model or via fraction method?
Thanks

you can use any approach - fraction, ratio, model, units..

using fraction:
children who like chocolate ice-cream --> 5/11 total
children who like vanilla and strawberry ice-cream--> 6/11 total
children who like vanilla ice cream --> 1/4 x 6/11 = 6/44 total
children who like strawberry ice cream --> 3/4 x 6/11 = 18/44 total
5/11 - 6/44 = 14/44
14/44 total --> 182
Total number of children = 182/14 x 44 = 572

using ratio:
children who like chocolate : total : vanilla & strawberry = 5 : 11 : 6 = 10u : 22u : 12u
children who like vanilla : strawberry = 1 : 3 = 3u : 9u (total 12u)
10u - 3u = 7u --> 182
total number of children = 22/7 x 182 = 572

cheers.

You wrote \"children who like vanilla ice cream --> 1/4 x 6/11 = 6/44 total \"
can u help to explain how the 1/4 is being derived? Thanks[/quote]5/11 total like chocolate
remainder (=6/11 total) like vanilla and strawberry

of the remainder (total 4 parts-1 part vanilla + 3 parts strawberry),
1 part likes vanila --> 1/4 remainder = 1/4 x 6/11 total
3 parts likes strawbarry --> 3/4 remainder = 3/4 x 6/11 total

using model:

http://i45.tinypic.com/359bmdi.png\">

cheers.

[snowball]

quote]


You wrote \"children who like vanilla ice cream --> 1/4 x 6/11 = 6/44 total \"
can u help to explain how the 1/4 is being derived? Thanks[/quote]

1/3 as many children like vanilla ice cream as those who like strawberry ice cream

My understanding is, 1/3 like vanilla and 2/3 like strawberry!! :sad:

Above english sentence make me confused! Worried that the kids might interpret wrongly if their english is as lousy as mine