# Macaulay Duration: Duration for 2 bonds

Using Macaulay Duration, determine the duration of Bond B if Bond A and B (market value of 600 000 dollars and 400 000 dollars respectively) have a duration of 6.7 years and the duration of A is 8.5 years.

My thinking:

Since duration looks at the time of maturity of the bond prices, Bond A and B's duration will be inter-linked. Hence, I will be able to write µ(ab) ≠ µ(a) or µ(b).

But if that is the case, then I would be unable to draw a link to the two equations between Bond A and B and Bond A?

Is my thinking correct in finding duration of Bond B?

$MacD(A,B)=\frac{V(A) \cdot MacD(A)+ V(B) \cdot MacD(B)}{V(A)+V(B)}$