You can use a combination of a row level calculation and a level of detail calculation. The level of detail calculation can be used to flag the quarters which have both a lapsed and inforced status. Once these quarters are flagged you can calculate the lapsed rate at a row level which can then be rolled up using a sum.

Create a calculated field as follows: Let me know if you have any questions or need any tweaks.

if
avg(
// Calculate the number of Inforce/Lapsed occurences per Quarter
IF
[Status] = 'Inforce'
or
[Status] = 'Lapsed'
then
{ FIXED
DATEPART('quarter', [Date]):
countd([Status])
}
else
0
end)
//
= 2
then
// Calculate the Lapsed Rate as both statuses exist in the quarter
sum((if
[Status] = 'Lapsed'
then [Total Amount]
END))
/
sum([Total Amount])
END