your data:

Your first FAS sample weighed $0\mathrm{.}7305$ grams.

The burette starting volume was $2\mathrm{.}68mLs$

The burette reading at the titration end point was $21\mathrm{.}31mLs.$

Calculate your periodate concentration.

Your second FAS sample weighed $0\mathrm{.}7445$ grams.

The burette starting volume was $1\mathrm{.}40mLs$

The burette reading at the titration end point was $20\mathrm{.}4mLs.$

Calculate your periodate concentration.

Your third FAS sample weighed $0\mathrm{.}7249$ grams.

The burette starting volume was $1\mathrm{.}00mLs$

The burette reading at the titration end point was $19\mathrm{.}49mLs.$

Calculate your periodate concentration.

Calculate and report your average periodate concentration.