In order to test the hypothesis that the girls in her class are taller than the boys, mary measures the heights of the first five girls and five boys listed on the class register. she finds the mean height of the girls is 162cm and the mean height of the boys is 158cm. is she justified in believing her hypothesis has been confirmed? justify your answer fully. how would you have designed an investigation to test the hypothesis?

i'm quite stuck on the second question. in the first part, i talked about sample being too small/randomness of sample etc any would be much appreciated: )