Q3 of 145 Page 370

Compute the mean of the following data:

















Class



1 - 3



3 - 5



5 - 7



7 - 9



Frequency



12



22



27



19


For equal class intervals, we will solve by finding mid points of these classes using direct method.







































CLASS



MID - POINT(xi)



FREQUENCY(fi)



fixi



1 - 3



2



12



24



3 - 5



4



22



88



5 - 7



6



27



162



7 - 9



8



19



152



TOTAL




80



426




We have got


Σfi = 20 & Σfixi = 426


∵ mean is given by



⇒


⇒


Thus, mean is 5.325


More from this chapter

All 145 →
1

If the mean of 5 observations x, x + 2, x + 4, x + 6 and x + 8 is 11, find the value of x.

 2

If the mean of 25 observations is 27 and each observation is decreased by 7, what will be the new mean?

 4

Find the mean, using direct method:





















Class



0 - 10



10 - 20



20 - 30



30 - 40



40 - 50



50 - 60



Frequency



7



5



6



12



8



2


 5

Calculate the mean of the following data, using direct method:



















Class



25 - 35



35 - 45



45 - 55



55 - 65



65 - 75



Frequency



6



10



8



12



4