Abookcase costs $93.11 when the cpi is 191. what is the cpi when a bookcase costs $76.05?
a.
213
b.
181
c.
156
d.
122

The value of the CPI (Consumer Price Index) is calculated by dividing first the current period price by the base period price and multiply the quotient by 100. Using the first set of values, we get base period price. 
                                CPI = (current period price / base period price) x 100
                                 191 = (93.11 / base period price) x 100
                                          base period price = 48.75

Then, using this base period price and the second current period price, we solve for the second CPI
                                CPI = (76.05 / 48.75) x 100
                                  CPI = 156
Therefore, the answer to this item is letter C.