Answer:
28 or 28.11111 because I don't know if it asked you to round or not.
Explanation:
Mean is the average of a group of number added together and divided by the number of number there are.
20+22+25+28+29+30+32+33+34 = 253
Now we will divide by the number of numbers we have there are 9 numbers.
Soooo.
253/9= 28.1111111
(Round)
28