combined mean
nx,ny number of people
,
means
group a
the number of people - 35
mean - 75
group b
the number of people - 55
mean - 95
combined mean |
= |
(35·75+55·95) |
/ |
(35+55) |
= |
87.22 |
one number was added to the data the number 60 what will be the new standard deviation
combined mean |
= |
(90·87.22+1·60) |
/ |
(90+1) |
= |
86.92 |