Biology · Grades 8–11
Percentage mass change
Use initial mass in the denominator. A negative percentage represents a decrease from the starting mass.
Rule and assumptions
Use initial mass in the denominator. A negative percentage represents a decrease from the starting mass.
(final − initial)/initial × 100
Worked examples
Supplied plant-tissue data show initial mass 10.8 g and final mass 11.7 g. Find signed percentage mass change. No experiment is required. Round to 3 decimal places if needed. Answer in %.
(final − initial)/initial × 100 (11.7 − 10.8)/10.8 × 100 = 8.333
8.333 %
Supplied plant-tissue data show initial mass 9 g and final mass 10.2 g. Find signed percentage mass change. No experiment is required. Round to 3 decimal places if needed. Answer in %.
(final − initial)/initial × 100 (10.2 − 9)/9 × 100 = 13.333
13.333 %
Try two questions
Supplied plant-tissue data show initial mass 5.4 g and final mass 8.1 g. Find signed percentage mass change. No experiment is required. Round to 3 decimal places if needed. Answer in %.
Supplied plant-tissue data show initial mass 14.9 g and final mass 15.6 g. Find signed percentage mass change. No experiment is required. Round to 3 decimal places if needed. Answer in %.
Answers and reasoning
Answers and marking notes
- 50 %
(final − initial)/initial × 100 (8.1 − 5.4)/5.4 × 100 = 50
- 4.698 %
(final − initial)/initial × 100 (15.6 − 14.9)/14.9 × 100 = 4.698
Further reading and review references
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Learning preview · independent educational and translation review required. Suggested grades are not official curriculum alignment.