Question

solve this with full
method

Answer 1

using the direct method:

Mean=34, Sum of frequencies=35

Mean=Sum of fi×xi/Sum of fi

34=40+20f1+240+40f2+150+240/19+f1+f2

34(19+f1+f2)=670+20f1+40f2

646+34f1+34f2=670+20f1+40f2

34f1-20f1+34f2-40f2=670-646

14f1-6f2=24

7f1-3f2=12 ...........(1)

19+f1+f2=35..........(2)

Solving both the equations:

In eq. (1) f1=12+3f2/7........(3)

Substituting (3) in (2)

19+(12+3f2)/7+f2=35

=145+10f2=245

f2=100/10=10...........(4)

Substituting (4) in (3)

f1=12+30/7=42/7=6

F1=6 F2=10. Ans.