Solution

Expected value 

$$= E(X)= \Sigma xf(x)= 0\times 0.1+1\times 0.4 + 2\times 0.4 + 3\times 0.1 = 1.5

=E(X)=Σxf(x)=0×0.1+1×0.4+2×0.4+3×0.1=1.5 

The average number of people visiting the store is equal to the expected value

Answer

The person visits the store an average of $1.5$ times