Question

Mean score of $25$ observation is $80$ and that of another $75$ observation is $60$ The mean score of all observation taken together is

• A. $65$
• B. $75$
• C. $85$
• D. None of these above

Answer 1

The correct option is A $65$

Sum of value $=25\times 80+75\times 60=6500$
Number of observation $=25+75=100$
Combined mean = $\frac{Sumofvalue}{Numberofobservations}$ $=\frac{6500}{100}=65$