If a CMO has $3$ tranches, A$,$ B$,$ and Z $($an accrual tranche$),$ as

well as a residual class, answer the following question?If the prepayment on a pool of mortgages$$decreases from CPR

$10\%$ to CPR $5\%,$ what would happen to the expected maturity of the A

class?Increase, decrease, or stay the same?$$