Find the mean of the following data, using assumed-mean method:
Class0−2020−4040−6060−8080−100100−120Frequency203552443831
Solution:
ClassFrequency(fi)Mid values (xi)Deviation(di=xi−50)fidi0−202010−40−80020−403530−20−70040−605250=A0060−8044702088080−1003890401520100−12031110601860∑fi=220∑fidi=2760
Let A= assumed mean =50.
Mean, ¯¯¯x=A+∑fidi∑fi
=50+2760220
=50+12.55
=62.55
Hence, the mean of the given data is 62.55