For each of the following, state the null and alternative hypotheses.

(a) The mean length of a piece of ribbon increased to above 15 cm.

(b) The population proportion is the same as the historical value of 50%.

(c) The average height of a 32-year-old male in a community is claimed to be at most 180 cm.

(d) The proportion of healthy children in a community is believed to be less than 75%.

(e) The average weight of people in a community is 85 kg.