Question

if the mean of the following data is 21 find the missing frequency f

X. Y
10. 6
15. 10
20. F
25. 10
30. 8

Answer 1

answer is 70 of missing frequency

Answer 2

Answer: F=14

Step-by-step explanation:

Given table :  

X.              Y              XY

10.             6              60

15.            10            150

20.            F             20F

25.           10             250

30.            8            240

$\text{Now, Mean = }\dfrac{\sum XY}{\sum Y}=\dfrac{700+F}{34+F}\\\\\Rightarrow\ 21=\dfrac{700+F}{34+F}\\\\\Rightarrow\ 21(34+F)=700+F\\\\\Rightarrow\ 714+21F=700+F\\\\\Rightarrow\ F=14$