Answer:So the new  Market price of the security =$49.41
Explanation:
In line with the Capital Asset Pricing Model CAPM, we have that Â
Expected return= risk free rate+(betaXmarket risk premium)
12=7+ beta x 7
= 12-7 = beta x 7
beta = 5/7 =0.714
IF Â beta doubles with other variables constant
 Expected return= risk free rate+(betaXmarket risk premium)
Beta= 0.714 x2 =1.4285
Expected return = 7 + 1.4285 x 7
Expected return 7+ 9.9995=16.995 ≈17%
Price  =  Perpertual Dividend /Expected retrn
where Current Share price =$70
Dividend = $70 x 12%= $8.4
The new Market price = Â Perpetual dividend/Required return
= 8.4/17% =$49.41
So the new Market price =$49.41