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Then this is the expected price for the  weekly shipment of rats =13.25

Step-by-step explanation:

Suppose the price for the shipment of rats are as follow

price 10 12.50 15

and probability may be

0.2  0.3  0.5

then the expected value is equal to

=10* 0.2 + 12.50 *0.3 + 15 *0.5

=13.25

then this is the expected price for the  weekly shipment of rats