please help with the attached, the inequalities for either hypothesis can be changed to any = ect

Suppose certain electronic components require gold leaf to produce - say with standard deviation o = 20 cm' and unknown mean. We want to test, in an unbiased way, whether the mean amount of gold leaf required per component is 25 cm', and are given the information that for a particular sample of size 79 (supposed to be independent and identically distributed) we have sample mean 28 cm. Give appropriate null and alternative hypotheses for this problem. In cm', the null hypothesis is Ho : A while the alternative hypothesis is H1 :Suppose certain electronic components require gold leaf to produce - say with standard deviation " = 20 cm' and unknown mean. We want to test whether the mean amount of gold leaf required per component is 25 cm, and are given the information that for a particular sample of size 79 (supposed to be independent and identically distributed) we have sample mean 28 cm?. Assuming the null hypothesis from the last exercise holds, specify an expression for the standardised version Z of the estimator X, of / such that Z~N(0, 1). Then calculate the observed value z of the test statistic, and the P-value. In terms of Y = Xn a suitable test statistic is Z = The observed value of the test statistic is (to 2 decimal places) 2 ~ The P-value is (to 4 decimal places) approximately