Caculate the mode from the following data :
`{:("Wages (Rs.)",0-5,5-10,10-15,15-20,20-25,25-30,30-35),("Number of Workers"," "3," "7," "15," "30," "20," "10," "5):}`

Explanation

Since, the sercies is regular, we may not do grouping for the locatiob of model group . By inspection , model class is 15-20.
`Z=l_(1)+(f_(1)-f_(0))/(2f_(1)-f_(0)-f_(2))xxi`
Here , `l_(1)=15,f_(1)=30,f_(0)=15,f_(2)=20,i=5`
Substituting the values , we get
`Z=15+(30-15)/(2(30)-15-20)xx5`
`=15+(15)/(60-35)xx5`
`=15+(15)/(25)xx5`
=15+3=18`
Thus , Mode =18.