Question Number 183117 by Subhabrata last updated on 20/Dec/22
Answered by Rasheed.Sindhi last updated on 21/Dec/22
$$\begin{array}{|c|c|c|c|c|c|c|c|c|}{{Class}}&\hline{{x}_{{i}} }&\hline{{f}_{{i}} }&\hline{{x}_{{i}} {f}_{{i}} }\\{\mathrm{30}−\mathrm{39}}&\hline{\mathrm{34}.\mathrm{5}}&\hline{\mathrm{2}}&\hline{\mathrm{69}}\\{\mathrm{40}−\mathrm{49}}&\hline{\mathrm{44}.\mathrm{5}}&\hline{\mathrm{3}}&\hline{\mathrm{133}.\mathrm{5}}\\{\mathrm{50}−\mathrm{59}}&\hline{\mathrm{54}.\mathrm{5}}&\hline{\mathrm{11}}&\hline{\mathrm{599}.\mathrm{5}}\\{\mathrm{60}−\mathrm{69}}&\hline{\mathrm{64}.\mathrm{5}}&\hline{\mathrm{20}}&\hline{\mathrm{1290}}\\{\mathrm{70}−\mathrm{79}}&\hline{\mathrm{74}.\mathrm{5}}&\hline{{f}_{\mathrm{5}} }&\hline{\mathrm{74}.\mathrm{5}{f}_{\mathrm{5}} }\\{\mathrm{80}−\mathrm{89}}&\hline{\mathrm{84}.\mathrm{5}}&\hline{\mathrm{25}}&\hline{\mathrm{2112}.\mathrm{5}}\\{\mathrm{90}−\mathrm{99}}&\hline{\mathrm{94}.\mathrm{5}}&\hline{\mathrm{7}}&\hline{\mathrm{661}.\mathrm{5}}\\{}&\hline{}&\hline{\underset{=\mathrm{68}+{f}_{\mathrm{5}} } {\Sigma{f}_{{i}} }}&\hline{\underset{=\mathrm{4866}+\mathrm{74}.\mathrm{5}{f}_{\mathrm{5}} } {\Sigma{x}_{{i}} {f}_{{i}} }}\\\hline\end{array} \\ $$$${A}.{M}.=\frac{\Sigma{x}_{{i}} {f}_{{i}} }{\Sigma{f}_{{i}} }=\frac{\mathrm{4866}+\mathrm{74}.\mathrm{5}{f}_{\mathrm{5}} }{\mathrm{68}+{f}_{\mathrm{5}} }=\mathrm{72}.\mathrm{5} \\ $$$$\:\:\:\:\:\:\:\mathrm{4866}+\mathrm{74}.\mathrm{5}{f}_{\mathrm{5}} =\mathrm{4930}+\mathrm{72}.\mathrm{5}{f}_{\mathrm{5}} \\ $$$${f}_{\mathrm{5}} =\frac{\mathrm{4930}−\mathrm{4866}}{\mathrm{2}}=\mathrm{32} \\ $$
Answered by cortano1 last updated on 21/Dec/22
