Answer:
- The mean length of 10 children's big finger is 8.1 cm
Average length of all the 10 children's finger is (8.1×10) cm = 81 cm.
- The mean length of 11 adult's big finger is 14.1 cm
Average length of all the 11 adult's big finger is (14.1×11) cm =155.1
- Mean length of these 21 people's big finger is
- Hence, <em><u>11.24</u></em> is the right answer.