Hi Tatiana,
The formula for CPI is
CPI = Earned Value / Actual Cost
Earned Value = Completed Panels * Fixed Price per panel
Earned Value = 350 * 75 = $26,250
Actual Cost = $45,000
CPI = 26250 / 45000 = 0.583
So this eliminates the first option (a).
Similarly, you would realise that we can also eliminate option (b) by calculation.
Now coming to option (c)
The formula for TCPI is
TCPI = Work Remaining / Funds Remaining
Work Remaining = Total Work - Work Done
Work Remaining = Total Panels - Completed Panels
Work Remaining = 900 - 350
Work Remaining = 550 panels
Work Remaining in $ terms = 550 * 75 = $41,250
Funds Remaining = Total Funds - Already Spent
Funds Remaining = (900*75) - 45000
Funds Remaining = 67500 - 45000
Funds Remaining = $22,500
Therefore TCPI = 41250 / 22500
TCPI = 1.833
TCPI basically means projecting what cost performance project needs to achieve in order to active the budget targets. In other words, what should be our projected CPI to ensure that the project work is completed within the original budget (which in this case is 900 * 75 = $67,500)
Hope this helps.