l. (20 points) We have three Bonds Bi, B2 and B, with durations Di-4, D. 5 and D3 6. Can we form a portfolio that is immune to small variations of the discount rate r that would help us meet a debt-obligation that is due 7 time-units into the future? How many portfolio-choices do we have, assuming no short- selling is permitted 2. (20 points) As a follow-on to problem 1, can we form a portfolio that is immune to small variations of the discount rate rthat would help us meet a debt-obligation that is due 3 time-units into the future? How many portfolio-choices do we have, assuming no short-selling is permitted. 3. (20 points) As a follow-on to problem 1, can we form a portfolio that is immune to small variations of the discount rate rthat would help us meet a debt-obligation that is due 4 time-units into the future? How many portfolio-choices do we have, assuming no short-selling is permitted. 4. (40 points) As a follow-on to problem 1, can we form a portfolio that is immune to small variations of the discount rate rthat would help us meet a debt-obligation that is due 5 time-units into the future? How many portfolio-choices do we have, assuming no short-selling is permitted. l. (20 points) We have three Bonds Bi, B2 and B, with durations Di-4, D. 5 and D3 6. Can we form a portfolio that is immune to small variations of the discount rate r that would help us meet a debt-obligation that is due 7 time-units into the future? How many portfolio-choices do we have, assuming no short- selling is permitted 2. (20 points) As a follow-on to problem 1, can we form a portfolio that is immune to small variations of the discount rate rthat would help us meet a debt-obligation that is due 3 time-units into the future? How many portfolio-choices do we have, assuming no short-selling is permitted. 3. (20 points) As a follow-on to problem 1, can we form a portfolio that is immune to small variations of the discount rate rthat would help us meet a debt-obligation that is due 4 time-units into the future? How many portfolio-choices do we have, assuming no short-selling is permitted. 4. (40 points) As a follow-on to problem 1, can we form a portfolio that is immune to small variations of the discount rate rthat would help us meet a debt-obligation that is due 5 time-units into the future? How many portfolio-choices do we have, assuming no short-selling is permitted