Help pls!

Your project exceeded costs in the past caused by an underestimation of resource costs in the cost baseline:
PV: $1,200,000, EV: $1,000,000, AC: $1,200,000
You expect the underestimation to influence the future as much as it did in the past.
If the value of the remaining work (BAC – EV) is at $1,000,000, what should be your new EAC (estimate at completion)?
 
$1,800,000 o $2,000,000 o $2,200,000 o $2,400,000
 
The correct answer is 4 which is 2,400,000. How did they arrive at this and which formulas was used. Cause I used AC+ (Bac-Ev) which happen to be option 2 
 

"You expect the underestimation to influence the future as much as it did in the past."

Formulato be used is: BAC/CPI(cumulative)=EAC

BAC-EV =1000000
AV = 1200000
EV = 1000000
PV=  1200000
 
BAC/CPI=EAC
 
CPI = EV/AC = 1000000/1200000= .83
 
BAC-EV =1000000
BAC = 1000000 + EV
BAC = 1000000 + 1000000
BAC = 2000000/.833
 
EAC = 2400000

BAC-EV =1000000
AV = 1200000
EV = 1000000
PV=  1200000
 
BAC/CPI=EAC
 
CPI = EV/AC = 1000000/1200000= .833
 
BAC-EV =1000000
BAC = 1000000 + EV
BAC = 1000000 + 1000000
BAC=2000000
 
 
EAC=BAC/CPI
EAC = 2000000/.833
 
EAC = 2400000

Thanks. Much appreciated.