find the median from the foll.data

x 5 10 15 20 25 30 35

f 1 3 17 20 10 5 4

X                                             FREQUENCY                                                       CUMULATIVE FREQUENCY

5  1  1

10  3  4

15  17  21

20  20  41

25  10  51

30  5  56

35  4  60

HERE n=60

So, size of (N+1)/2^TH item

=>size of (60+1)/2^TH item ie 61/2^th item

=>size of 30.5^th item

Now we know that 30.5^th item lies in 41 cf

Therefore, the median=20 {SINCE THE VALUE OF X CORRESPONDING TO THE (N+1)/2^TH ITEM REPRESENTS THE MEDIAN VALUE}