For each of the following, state the null and alternative hypothesis. You do not have to run any statistical analysis. (a) According to the US Census Bureau, 11.8% of registered birth in the United States in 2010 were to teenage mothers. A sociologist claims that the proportion is greater. A simple random sample of 200 registered births in 2017 revealed that 13% were to teenage mothers.
(b) The standard deviation in the pressure required to open a certain type of valve is known to be 0.07 psi. Due to changes in the manufacturing process, the quality-control engineer feels that the standard deviation in the pressure required to open the valve has now changed.
(c) According to the Statistical Abstract of the United States, the mean consumption of fruits in 2005 was 98.4 pounds. A dietician believes that more people are becoming health conscious and that fruit consumption has risen since then.