Cost Performance Index = ratio of earned value over how much we actually spent to date. A ratio of 1 means we are on track. A ratio of <1 means we are running behind, and a ratio of >1 means we are ahead.
ETC = Estimated Cost to Completion
BAC = Budget at Completion (baseline)
EV = Earned Value
CPI = Cost Performance Index
First, let's calculate the Cost Performance Index, which is a ratio of earned value divided by how much we actually spent.
$3,000 / $3500 = 0.857
Since our ratio is <1, we are running a bit behind.
Next, let's determine the remaining estimated cost to completion using the equation in the hint section.
($5,000 - $3,000) / 0.857 = $2,333.72
Total estimated cost at completion (how much we spent + our projected remaining costs):
$3,500 + $2,333.72 = $5,833.72
Finding the extra cost at the current rate:
$5,833.72 - $5,000 = $833.72
Total Estimated Cost at Completion = $5,833.72
Extra Cost at Current Rate = $833.72