Sign Up!
Login
Welcome to Test-paper.info
Friday, July 21 2017 @ 09:30 PM CDT
 Forum Index >  Test Paper Related >  Primary 6 Matters
 Maths Question 1
   |  Printable Version
By: shirley wee (offline)  Sunday, April 07 2013 @ 07:03 AM CDT (Read 765 times)  
shirley wee

Hi everybody! I'm stuck with this maths question. May you help me? Please show your working clearly.

Qn 1. In a Science test, the average marks of all the pupils in Class 6A was 86. After 4 pupils who scored an average of 71 marks left the class, the average marks of the remaining pupils became 88. How many pupils were there in Class 6A at first?

Forum Chatty
Chatty

Registered: 02/28/12
Posts: 68

Profile Email    
   
By: echeewh (offline)  Sunday, April 07 2013 @ 09:28 AM CDT  
echeewh

Hey Shirley,

Following pls find my worked solution:

Let number of pupils in 6A be 1u.

Total marks = 86u
Marks of 4 pupils left = 4 × 71 = 284
Average marks of remaining pupils = (86u - 284) ÷ (u - 4)

Given average marks of remaining pupils is 88, we have ...

(86u - 284) ÷ (u - 4) = 88
86u - 284 = 88 × (u - 4)
86u - 284 = 88u - 352
88u - 86u = 352 - 284
2u = 68
u = 34

Hence, number of pupils in 6A = 34

==========

Trust this helps.

Kindly let me know again if this is different from your Answerkey or if theres further clarification.

Cheers,
Edward

Forum Active Member
Active Member

Registered: 04/21/11
Posts: 623

Profile Email    
   


 All times are CDT. The time is now 09:30 pm.
Normal Topic Normal Topic
Locked Topic Locked Topic
Sticky Topic Sticky Topic
New Post New Post
Sticky Topic w/ New Post Sticky Topic w/ New Post
Locked Topic w/ New Post Locked Topic w/ New Post
View Anonymous Posts 
Able to Post 
HTML Allowed 
Censored Content