When a shunt with a resistance of 100 ohms is connected parallel to the measuring device, the needle deflects to the full scale at a current in the external circuit of 3 A. When an additional resistance of 300 ohms is connected to an unshunted galvanometer, the scale of the device becomes four times coarser than without the additional resistance and shunt. What shunt should be used so that the needle deflects to the full scale when the current in the external circuit is 7.5 A?

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