How did speculative investing weaken the stability of the stock market

Can someone me with the property questions for 12 13 and 14 plz

Atextile fiber manufacturer is investigating a new drapery yarn, which the company claims has a mean thread elongation of 12 kilograms with a standard deviation of 0.5 kilograms. the company wishes to test the hypothesis upper h subscript 0 baseline colon mu equals 12 against upper h subscript 1 baseline colon mu less-than 12 using a random sample of n equals 4 specimens. calculate the p-value if the observed statistic is x overbar equals 11.8. round your final answer to five decimal places (e.g. 98.76543).

How can you find the magnitude of a vector, v = < x,y > , where the horizontal change is x and the vertical change is y?