Please help me solve the following, I need the steps so that I can do them myself. Let me know how many credits will be required.

1.) Find the critical z value, assume that the normal distribution applies.

alpha = 0.005; H1 is p not equal 0.20

2.) In 1990, 5.8% of job applicants who were tested for drugs failed the test. At the 0.01 significance level, test the claim that the failure rate is now lower if a simple random sample of 1520 current job applicants results in 58 failures. Does the result suggest that fewer job applicants now use drugs?

3.) Claim: The mean life span of desktop PC's is less than 7 years. Sample data: n=21, mean of the value = 6.8 years, s = 2.4 years. The significance level is alpha = 0.05.

Find the null and alternative hypothesis, test statistic, critical value, and state the final conclusion. Assume that a simple random sample has been selected from a normally distributed population