The arithmetic mean of the 12,78,87,92 is?

Mean = \(\frac{ sum \; of \;  observations }{ number \; of \; observations }\)

Mean = \(\frac{ 12 + 78 + 87 + 92 }{ 4 }\)

Mean = \(\frac{ 269}{ 4 }\)

Mean = 67.25