Answer
The second store
Work Step by Step
By definition, the expected value is the sum of each outcome multiplied by its probability.
Hence here the expected value for the first store: $\frac{1}{2}\cdot300000+\frac{1}{2}\cdot(-100000)=100000$, the expected value for the second store: $\frac{3}{4}\cdot200000+\frac{1}{4}\cdot(-60000)=135000$. The second store has a higher expected value, thus they should choose that one.
