Final answer:
Decreased household income leads to lower demand for Blackberry Cell Phones, a normal good, shifting the demand curve leftward. For an inferior good, demand would increase, shifting the demand curve rightward.
Step-by-step explanation:
When household income decreases and we assume that Blackberry Cell Phones are a normal good, the demand for Blackberries would decrease. Graphically, this is represented by a leftward shift of the demand curve. If Blackberry Cell Phones were an inferior good, a decrease in income would result in a(n) increase in demand, which would be shown as a rightward shift in the demand curve. This relationship is based on the income effect, where normal goods see a rise in demand as income increases, whereas demand for inferior goods rises when income decreases.