In the question of 6, I found the skewness was negative as mean is smaller than median. This is because that P(x>E(x)) is greater than 0.5 so the value of e(x) has to be smaller than the value of median. (Not sure though.) P(x<E(x) was also 0.4xxxx.. In this question, was the mode 7 ? as f(x) = x^2/90 - x/90 ; 5.4 of mean is smaller than 7 of mode, showing mean is smaller than mode as well. Therefore, Mean < median < mode is proved. Am i wrong..?
In the question of 7(B), which one was i supposed to use between two and one tailed ? My approach was two - tailed one, finding 0.0342 is bigger than 0.025, which shows there is less evidence to claim that the rate of fish caught has been changed after buying the equipment. The reason why i used two-tailed was there was no explicit mention about increase. The question just said that there was any change after buying equipment.
Could anyone tell me whether i am right or not ? Please!!