Q&A - P3 Math

[iFruit]

imacsg:

Can someone tell me why a eight equal sides octogen cannot be tessellated?

Thanks

In a tessellation, the objects around a vertex must fit exactly without overlap. That means the interior angles of all the polygons meeting at a vertex must equal to 360.

For example,
In an equilateral triangle, corners of 6x triangles make 360 degrees at the vertex(6 x60)

for square, it's the corners of four squares that make a vertex (4x90)

For an octagon, the interior angle is 135 degrees. 3 x 135 = 405 and 2x 135 = 270. So, a tessellation can't be formed.

PS: An interesting formula to remember: Interior angle of a regular polygon = 180x(n-2)/n where n= number of sides.

HTH

[femi]

tianzhu:

[quote]2)Mrs Raja gave 17 boys and girls a total of 105 clips. Each boy was given 5 clips and each girl was given 7 clips.If all the girls were to give all their clips to the boys, how many more clips would each boy get?

Hi
Hope this helps.

You may use a heuristics known as Making a Supposition or Assuming Method.

Suppose all the 17 pupils are girls.

17*7 = 119
119 – 105 = 14 (fewer clips)

Each boy has 2 fewer clips.
Number of boys = 14/2 = 7

Number of girls = 10
Number of clips held by girls = 7*10 = 70

Hence each boy will get 70/7 = 10 clips (more)

Best wishes[/quote]

thanks for your help :lol: :celebrate: :love: :?: :idea:

[femi]

can somebody help me in these questions pls?this are primary 4 questions.


question 1)Arvin has 6 times as many cards as Cedric. if Arvin gives 40 cards to cedric, they will have the same number of cards. How many cards should Alvin give to Cedricc so that he has thrice as many cards as Cedric?


question 2)mrs ida baked 125 tarts and placed them in a jar. Aliff ate 4 tarts everyday.Fatimah ate 1 tart on the first day,2 tarts on the 2nd day,3 tarts on the 3rd day and so on.
a)on which day would both children have eaten the same total number of tarts?
b)how many tarts are left in the jar on day 10?



hope u can answer the questions.
thanks :lol: :oops: :roll: :? :shock: :idea: :?: :!: :stupid: :celebrate: [/list][/list]

[imacsg]

Hi ifruit,

Thanks. interesting formula to remember.

[tianzhu]

femi:

tianzhu:

[quote])Aminah and Shanthinee had 128 bookmarks altogether.Aminah gave 1/4of her bookmarks to Geraldine. Shanthinee have the same number of bookmarks left. How many bookmarks had shanthinee have at first?

Hi

Are the bookmarks given to Geraldine or Shanthinee?

Please confirm if the numbers are 128 and 1/4.

Best wishes

sorry, after the Aminah gave 1/4 of her bookmarks to Geraldine,Shanthinee gave 37 of her bookmarks to geraldine.now , ....... ....... ..... .....[/quote]Hi

Hope this helps.

Best wishes.

http://farm5.static.flickr.com/4113/5065785853_538870dd9e_b.jpg\">

[2DMommy]

pls help me with this question :


1/4 + 3/4 = 1
1/8 + 3/8 + 5/8+7/8 = 2
1/12 + 3/12 + 5/12 + 7/12 + 9/12 +11/12 = 3

Find the sum of :

1/208 + 3/208 + 5/208 + 7/208 …203/208 + 205/208 + 207/208

[Dharma]

2DMommy:

pls help me with this question :


1/4 + 3/4 = 1
1/8 + 3/8 + 5/8+7/8 = 2
1/12 + 3/12 + 5/12 + 7/12 + 9/12 +11/12 = 3

Find the sum of :

1/208 + 3/208 + 5/208 + 7/208 ......203/208 + 205/208 + 207/208

By looking at the pattern

1/208 + 3/208 + 5/208 + ...... + 207/208 = 52
Sum of series is the denominator divided by 4
So, 208 / 4 = 52

Check :

1 + 207 = 208
No. of pairs = 104/2 = 52
1/208 + 3/208 + 5/208 + ... + 207/208 = 52 x 208/ 208 = 52

[2DMommy]

Thanks Dharma !


Another question :

John and Peter had an equal number of stickers. After Peter gave 27 stickers to John, John had 4 times stickers as Peter. How many stickers did Peter have at first?

[Dharma]

2DMommy:

Thanks Dharma !


Another question :

John and Peter had an equal number of stickers. After Peter gave 27 stickers to John, John had 4 times stickers as Peter. How many stickers did Peter have at first?

John : 1u + 27 = 4p
Peter : 1u - 27 = 1p

4u - 108 = 1u + 27
3u = 135
1u = 45

Number of stickers Peter had at first =45

[2DMommy]

Another question :


Ahmad and Bata had a total of 7 cards at first. After Bata bought more cards and Ahmad lost cards, Bata now has 3 cards more than Ahmad. Find the number of cards Bata had at first?