Q&A - PSLE Math

[dicoyote]

Hi All,


I have a difficulty in this question, seeking help, thanks in advanced

\"The average height of a group of children was 139.4 cm

When Mr Tan measured and recorded the height of these children, he wrongly recorded one child's height as 192 cm when it should have been 129 cm.
As a result, Mr Tan calculated the average height as 142.4 cm.

How many children were there in the group?\"

[pixiedust]

dicoyote:

The average height of a group of children was 139.4 cm


When Mr Tan measured and recorded the height of these children, he wrongly recorded one child's height as 192 cm when it should have been 129 cm.
As a result, Mr Tan calculated the average height as 142.4 cm.

How many children were there in the group?

I'll give this a try but I can't draw the nice diagrams

Right Average = 139.4cm
Wrong Average = 142.4cm
Difference = 142.4cm - 139.4cm=3cm

Right Height = 129cm
Wrong Height = 192cm
Difference = 63cm
--> this is what contributed to the difference in average.

Hence, the number of children = 63/3=21

==================================
Check :
Right total=21x139.4=2927.40cm
Wrong total=21x142.4=2990.40cm
difference in total = 63cm <right>

[Michaelia0816]

dicoyote:

Hi All,


I have a difficulty in this question, seeking help, thanks in advanced

\"The average height of a group of children was 139.4 cm

When Mr Tan measured and recorded the height of these children, he wrongly recorded one child's height as 192 cm when it should have been 129 cm.
As a result, Mr Tan calculated the average height as 142.4 cm.

How many children were there in the group?\"

Use guess and check method, remember the total average number difference is 63, good luck at finding, I already found out the answer, simple!

[dicoyote]

Hi pixiedust and Michaelia0816,


Nice one, thanks for the speedy response, will run through the given suggestion, hope I can understand

[Michaelia0816]

I wish someone would like to solve my science question, I got a lot more!

[cimman]

dicoyote:

Hi All,


I have a difficulty in this question, seeking help, thanks in advanced

\"The average height of a group of children was 139.4 cm

When Mr Tan measured and recorded the height of these children, he wrongly recorded one child's height as 192 cm when it should have been 129 cm.
As a result, Mr Tan calculated the average height as 142.4 cm.

How many children were there in the group?\"

if you don't mind doing this in algebra, here's a solution using equations:

c = number of children
total value/c = 139.4
(total value + 63)/c = 142.4 (note: 63-> 142.4 - 129)
total value/c + 63/c = 142.4
139.4 + 63/c = 142.4
c = 21

[isetan]

MathIzzzFun:

kyp71:

[quote=\"kyp71\"]Please help anyone ?


The figures below is made up of a square, a quadrant and a semicircle. (take pie = 3.14)
(a) Find the perimeter of the shaded parts
(b) Find the difference in the area between the shaded parts.
http://i46.tinypic.com/1zxs7sj.jpg\">

Anyone can help me solve ?

Hi

I think you should be able to find the solution with this

http://i49.tinypic.com/344xv9g.png\">

note that such questions are actually same as \"age\" problems ie same gap/difference.

cheers.[/quote]Hi ,
Just attempt this question.....is the ans:-
For (a) 29.7
(b) 1.57

[Chan09]

http://i45.tinypic.com/2evthdd.jpg\"> help, tks

[tianzhu]

Chan09:

http://i45.tinypic.com/2evthdd.jpg\"> help, tks

Hi

Please refer to this similar question.

The answer to your question is 1/2.

Best wishes

http://farm7.staticflickr.com/6151/6191262010_71cc0ec1fd_z.jpg\">

[tianzhu]

isetan:

Hi ,
Just attempt this question.....is the ans:-
For (a) 29.7
(b) 1.57

Hi

We have the same answers.

Best wishes