Answer
 526.857
Step-by-step explanation
Mean = (Σfx)/(Σf)
Σfx = 248 + 2(567) = 3(1402) + 4(728) + 5(419) + 6(456) + 7(208)
 = 14,752
Σf = 1+2+3+4+5+6+7 
 = 28
Mean = (Σfx)/(Σf)
 = 14,752/28
 = 526.857
The estimated mean is the average of the data give. It is in form of a grouped data so I used to formula;
mean =  (Σfx)/(Σf)