Answer:

Step-by-step explanation:
The difference between two consecutive elements is 11.

Hence 
Answer:
4.21
Step-by-step explanation:
Because 2.1 is also equivalent to -4.2 which also is equivalent to D'.
7x-4x=10-1
3x=9
3/3x=9/3
x=3
Answer:
1. 13+18+13+14+13+16+14+21+13
= 145/9
=16.11
2. Range =145
3. Mode =13
4. Median =14
Step-by-step explanation: