I-spread with linear interpolation

[gsauls4]

This may be a very stupid question, but why when calculating a linear interpolation is the 2nd term divided by 0.5 as in the following…(which comes from Schweser notes book 4, page 152)
1.6 year swap rate =
1.5 yr swap rate +[ 0.1 (2yr swap rate - 1.5yr swap rate)/0.5]

 

[shootforthestars1]

^
Because 0.5 is the difference b/w 2 and 1.5 years

 

[gsauls4]

Yup, fatigue definitely setting in now!!!!

 

[shootforthestars1]

^No worries mate - take a break, I took the entire easter week off to prepare, relax and when I’m bored, AF

 

[CMLSML]

Ha Ha. Feeling stupid is surely part of the deal with clearing L2. Nice stories to tell your junior analysts!

 

[Pawan Punjabi]

I had the same issue, racked my brains for 20 mins figuring out 0.50 somewhere explicitly mentioned in the question .
Thanks.