Questions Q1. A person's heart beats approximately 10 5times each day. A person lives for approximately 81 years. (a) Work out an estimate for the number of times a person's heart beats in their lifetime. Give your answer in standard form correct to 2 significant figures. (2) 2 × 10 12red blood cells have a total mass of 90 grams. (b) Work out the average mass of 1 red blood cell. Give your answer in standard form