waecE-LEARNING
Home
Technical
Mathematics
Languages
Science
Social Science
Art
Literature Arabic Islamic Studies C.R.K HistoryMusicVisual Art Clothing/Textile Home Management Shorthand
 
Further Mathematics Paper 2, Nov/Dec. 2008  
Questions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Main
General Comments
Weakness/Remedies
Strength
Question 5

The deviations of the set of numbers from 55 are -5, -3, -1, 0, 1, 3, 5 and 7
Calculate the:
(a)        mean of the numbers.
(b)        variance of the numbers

_____________________________________________________________________________________________________
Observation

This question was well attempted by most candidates.  It was observed that candidates preferred the raw score method, which takes a longer time, to the deviation method.  This perhaps may be due to the lack of understanding of the deviation method. They were expected to apply the formula:
(a)        mean    =          A+Sd   where A = assumed mean, d = deviations from the assumed mean (given) and n = number of deviations        n      which gives mean  =  55 + 7/8  =  58.875. 

(b)  Variance  =  Sd2  -    Sd     2
                               n           n           where, d = deviations, d = mean of  the deviations and n = number of deviations
             which gives  = Sd2 =  25 + 9 + 1 + 1 + 9 = 25 + 49 = 119
             variance   =  119  -  49   =  14.875 - 0.7656 = 14.11 to 2 decimal places
                                      8       64

Powered by Sidmach Technologies(Nigeria) Limited .
Copyright © 2012 The West African Examinations Council. All rights reserved.