Today is 1 July 2020. Siobhán has a portfolio which consists of two different types of financial instruments (henceforth referred to as instrument A and instrument B). Siobhán purchased all...

Extracted text: Today is 1 July 2020. Siobhán has a portfolio which consists of two different types of financial instruments (henceforth referred to as instrument A and instrument B). Siobhán purchased all instruments on1 July 2011 to create this portfolio and this portfolio is composed of 26 units of instrument A and 45 units of instrument B. Instrument A is a zero-coupon bond with a face value of 100. This bond matures at par. The maturity date is 1 January 2030. Instrument B is a Treasury bond with a coupon rate of = 4.9% p.a. and face value of 100. This bond matures at par. The maturity date is 1 January 2023. Calculate the current duration of Siobhán's portfolio using a yield to maturity of = 4.39% p.a. Express your answer in terms of years and round your answer to two decimal places. a. 4,34 b. 5.73 c. 6.42 d. 4.13