How do i do these two types of problems? i know how to do mean, mode, and median. but these two just have me stumped. the one's bubbled in were my answer but they were wrong, explain what i should do.

What is the mean of the data set?
Data set:
393 ; 399 ; 402 ; 402 ; 407 ; 410 ; 424 ; 425 ; 428

393 + 399 + 402 + 402 + 407 + 410 + 424 + 425 + 428 = 3,690
3,690 / 9  = 410

The mean is 410. It is the average of all numbers.

What is the median of the data set?
Data set:
01 ; 03 ; 14 ; 15 ; 22 ; 35 ; 35 ; 43

There are 8 numbers, we need to get the sum middle 2 and divide it by 2 to get the median.

15 + 22 = 37
37/2 = 18.50

The median is 18.50

It’s going to be d. 4x^2-4x-19’