In order to find the required median, you first list the number divisible by 28 in between 1 and 1000. These numbers are:
28, 56, 84, 112, 140, 168, 196, 224, 252, 280, 308, 336, 364, 392, 420, 448, 476, 504, 532, 560, 588, 616, 644, 672, 700, 728, 756, 784, 812, 840, 868, 896, 924, 952, 980
Thus, you have 35 numbers divisible by 28. In this case you have an odd number of data. The median is the number at the position 18, which by the list above is 504.
Hence, the median is the integer 504