(a) I can't help you with using your calculator for this part, but if you have some familiarity with your device you can check your answer with mine.
The mean is simply the sum of all the house costs divided by the number of houses:
(75k + 75k + 150k + 155k + 165k + 203k + 750k + 755k)/8 = 291k
So the population mean is $291,000.
The population standard deviation is the square root of the population variance. To get the variance, you take the sum of all the squared differences between the cost and the mean cost, then divide that sum by the number of houses. That is,
[(75k - 291k)² + (75k - 291k)² + … + (755k - 291k)²]/8 = 581,286k
Note that the variances is measured in square dollars. Then the standard deviation is
√(581,286k) ≈ $762,421.1
(b) The median is just the price in the middle. There were 8 houses sold, so there are 2 "middle" prices. The median is the average of these:
(155k + 165k)/2 = 160k = $160,000
(c) Yes, the mode is the data that shows up most frequently. This happens at the lower end, with $75,000 appearing twice.