Maths-
General
Easy

Question

Consider the frequency distribution of the given number

If the mean is known to be ' 3 , then the value of f is

  1. 3    
  2. 7    
  3. 10    
  4. 14    

hintHint:

Use formula 
M e a n space equals space fraction numerator stack sum f subscript i x subscript i with blank below over denominator stack sum f subscript i with blank below end fraction

The correct answer is: 14


     Given :

    Mean = 3
    To find f, use formula
    M e a n space equals space fraction numerator stack sum f subscript i x subscript i with blank below over denominator stack sum f subscript i with blank below end fraction space equals space fraction numerator 1 cross times 5 space plus space 2 cross times 4 space plus space 3 cross times 6 space plus space 4 f over denominator 15 space plus space f end fraction
3 space equals space fraction numerator 31 space plus space 4 f over denominator 15 space plus space f end fraction

45 space plus space 3 f space equals space fraction numerator 31 space plus space 4 f over denominator blank end fraction
f space equals space 14
 

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