Test Index

ICSE Class X Math 2014 Paper

© examsnet.com
Question : 34 of 52
Marks: +1, -0
Calculate the mean of the distribution given below using the short cut method.
 Marks  No. of students
 11-20  2
 21-30  6
 31-40  10
 41-50  12
 51-60  9
 61-70  7
 71-80  4
Solution:  
 Marks(C.I.)  No. of students (f)  MeanValue(x)   d=x−Ad=x-A   f×df\times d
 11-20  2  15.5  -30  -60
 21-30  6  25.5  -20  -120
 31-40  10  35.5  -10  -100
 41-50  12  45.5  0  0
 51-60  9  55.5  10  90
 61-70  7  65.5  20  140
 71-80  4  75.5  30  120
   Î£f=50      Î£fd=70
Assumed mean =45.5=45.5
∵   Mean   =A+ΣfdΣf\because\; \text{ Mean }\; = A + \frac{\Sigma f d}{\Sigma f}
  =45.5+7050=45.5+1.4\; = 45.5 + \frac{70}{50} = 45.5 + 1.4
  =46.9\; = 46.9
© examsnet.com
Go to Question:
Prev Question
Next Question