The mode of the following series is 17.3 . Find the missing frequecny :

Explanation

Clearly 15-20 is the modal class as the mode 17.3 lies in this class.
Here, `l=15,f_(1)=24,f_(0)=x("say"),f_(2)=17 and h=5 and mode =17.3`
`"Mode(M)"=l+(f_(1)-f_(0))/(2f_(1)-f_(0)-f_(2))xxh`
`17.3=15+(24-x)/(2xx24-x-17)xx5`
`17.3=15+(24-x)/(31-x)xx5`
`2.3(31-x)=120=5x`
`2.3xx31-2.3x=120-5x`
5x-2.3x=120-17.3
2.7x=4.87
`x=(48.7)/(2.7)=18.03`
Hence, missing frequency is 18